diff --git a/java/src/com/android/inputmethod/latin/AbstractDictionaryWriter.java b/java/src/com/android/inputmethod/latin/AbstractDictionaryWriter.java
index 59d5569..e6fb980 100644
--- a/java/src/com/android/inputmethod/latin/AbstractDictionaryWriter.java
+++ b/java/src/com/android/inputmethod/latin/AbstractDictionaryWriter.java
@@ -60,10 +60,9 @@
     abstract protected void writeDictionary(final DictEncoder dictEncoder,
             final Map<String, String> attributeMap) throws IOException, UnsupportedFormatException;
 
-    public void write(final String fileName, final Map<String, String> attributeMap) {
-        final String tempFileName = fileName + ".temp";
-        final File file = new File(mContext.getFilesDir(), fileName);
-        final File tempFile = new File(mContext.getFilesDir(), tempFileName);
+    public void write(final File file, final Map<String, String> attributeMap) {
+        final String tempFilePath = file.getAbsolutePath() + ".temp";
+        final File tempFile = new File(tempFilePath);
         try {
             final DictEncoder dictEncoder = new Ver3DictEncoder(tempFile);
             writeDictionary(dictEncoder, attributeMap);
diff --git a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
index b52045e..4cc3165 100644
--- a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
@@ -144,20 +144,8 @@
         return mBinaryDictionary.isValidDictionary();
     }
 
-    protected String getFileNameToCreateDict(final String dictName) {
-        return dictName + DICT_FILE_EXTENSION;
-    }
-
-    protected String getFileNameToOpenDict(final String dictName) {
-        return getFileNameToCreateDict(dictName);
-    }
-
-    private File getFileToCreateDict() {
-        return new File(mContext.getFilesDir(), getFileNameToCreateDict(mDictName));
-    }
-
-    private File getFileToOpenDict() {
-        return new File(mContext.getFilesDir(), getFileNameToOpenDict(mDictName));
+    private File getDictFile() {
+        return new File(mContext.getFilesDir(), mDictName + DICT_FILE_EXTENSION);
     }
 
     /**
@@ -270,17 +258,14 @@
             public void run() {
                 if (mDictionaryWriter == null) {
                     mBinaryDictionary.close();
-                    final File file = getFileToCreateDict();
-                    file.delete();
+                    final File file = getDictFile();
+                    if (file.exists() && !FileUtils.deleteRecursively(file)) {
+                        Log.e(TAG, "Can't remove a file: " + file.getName());
+                    }
                     BinaryDictionary.createEmptyDictFile(file.getAbsolutePath(),
                             DICTIONARY_FORMAT_VERSION, getHeaderAttributeMap());
-                    // We have 'fileToOpen' in addition to 'file' for the v4 dictionary format
-                    // where 'file' is a directory, and 'fileToOpen' is a normal file.
-                    final File fileToOpen = getFileToOpenDict();
-                    // TODO: Make BinaryDictionary's constructor be able to accept filename
-                    // without extension.
                     mBinaryDictionary = new BinaryDictionary(
-                            fileToOpen.getAbsolutePath(), 0 /* offset */, fileToOpen.length(),
+                            file.getAbsolutePath(), 0 /* offset */, file.length(),
                             true /* useFullEditDistance */, null, mDictType, mIsUpdatable);
                 } else {
                     mDictionaryWriter.clear();
@@ -531,7 +516,7 @@
             }
         }
 
-        final File file = getFileToOpenDict();
+        final File file = getDictFile();
         final String filename = file.getAbsolutePath();
         final long length = file.length();
 
@@ -572,14 +557,14 @@
         if (needsToReloadBeforeWriting()) {
             mDictionaryWriter.clear();
             loadDictionaryAsync();
-            mDictionaryWriter.write(getFileNameToCreateDict(mDictName), getHeaderAttributeMap());
+            mDictionaryWriter.write(getDictFile(), getHeaderAttributeMap());
         } else {
             if (mBinaryDictionary == null || !isValidDictionary()
                     // TODO: remove the check below
                     || !matchesExpectedBinaryDictFormatVersionForThisType(
                             mBinaryDictionary.getFormatVersion())) {
-                final File file = getFileToCreateDict();
-                if (!FileUtils.deleteRecursively(file)) {
+                final File file = getDictFile();
+                if (file.exists() && !FileUtils.deleteRecursively(file)) {
                     Log.e(TAG, "Can't remove a file: " + file.getName());
                 }
                 BinaryDictionary.createEmptyDictFile(file.getAbsolutePath(),
@@ -706,8 +691,7 @@
 
     // TODO: cache the file's existence so that we avoid doing a disk access each time.
     private boolean dictionaryFileExists() {
-        final File file = getFileToOpenDict();
-        return file.exists();
+        return getDictFile().exists();
     }
 
     /**
diff --git a/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java b/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
index 8321df9..ceec3e1 100644
--- a/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
+++ b/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
@@ -112,16 +112,6 @@
         return formatVersion == REQUIRED_BINARY_DICTIONARY_VERSION;
     }
 
-    @Override
-    protected String getFileNameToCreateDict(final String dictName) {
-        return dictName;
-    }
-
-    @Override
-    protected String getFileNameToOpenDict(final String dictName) {
-        return dictName + "/" + dictName + FormatSpec.HEADER_FILE_EXTENSION;
-    }
-
     public void addMultipleDictionaryEntriesToDictionary(
             final ArrayList<LanguageModelParam> languageModelParams,
             final ExpandableBinaryDictionary.AddMultipleDictionaryEntriesCallback callback) {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.cpp
index dfb110c..c81c61d 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.cpp
@@ -16,11 +16,13 @@
 
 #include "suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.h"
 
+#include <climits>
 #include <stdint.h>
 
 #include "defines.h"
 #include "suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.h"
+#include "suggest/policyimpl/dictionary/structure/v4/ver4_dict_constants.h"
 #include "suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h"
 #include "suggest/policyimpl/dictionary/utils/file_utils.h"
 #include "suggest/policyimpl/dictionary/utils/format_utils.h"
@@ -32,9 +34,28 @@
         DictionaryStructureWithBufferPolicyFactory
                 ::newDictionaryStructureWithBufferPolicy(const char *const path,
                         const int bufOffset, const int size, const bool isUpdatable) {
-    // Allocated buffer in MmapedBuffer::newBuffer() will be freed in the destructor of
-    // MmappedBufferWrapper if the instance has the responsibility.
-    MmappedBuffer::MmappedBufferPtr mmappedBuffer = MmappedBuffer::openBuffer(path, bufOffset, size,
+    if (FileUtils::existsDir(path)) {
+        // Given path represents a directory.
+        return newPolicyforDirectoryDict(path, isUpdatable);
+    } else {
+        if (isUpdatable) {
+            AKLOGE("One file dictionaries don't support updating. path: %s", path);
+            ASSERT(false);
+            return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
+        }
+        return newPolicyforFileDict(path, bufOffset, size);
+    }
+}
+
+/* static */ DictionaryStructureWithBufferPolicy::StructurePolicyPtr
+        DictionaryStructureWithBufferPolicyFactory::newPolicyforDirectoryDict(
+                const char *const path, const bool isUpdatable) {
+    const int headerFilePathBufSize = PATH_MAX + 1 /* terminator */;
+    char headerFilePath[headerFilePathBufSize];
+    getHeaderFilePathInDictDir(path, headerFilePathBufSize, headerFilePath);
+    // Allocated buffer in MmapedBuffer::openBuffer() will be freed in the destructor of
+    // MmappedBufferPtr if the instance has the responsibility.
+    MmappedBuffer::MmappedBufferPtr mmappedBuffer = MmappedBuffer::openBuffer(headerFilePath,
             isUpdatable);
     if (!mmappedBuffer.get()) {
         return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
@@ -42,31 +63,70 @@
     switch (FormatUtils::detectFormatVersion(mmappedBuffer.get()->getBuffer(),
             mmappedBuffer.get()->getBufferSize())) {
         case FormatUtils::VERSION_2:
+            AKLOGE("Given path is a directory but the format is version 2. path: %s", path);
+            break;
+        case FormatUtils::VERSION_4: {
+            const int dictDirPathBufSize = strlen(headerFilePath) + 1 /* terminator */;
+            char dictPath[dictDirPathBufSize];
+            if (!FileUtils::getFilePathWithoutSuffix(headerFilePath,
+                    Ver4DictConstants::HEADER_FILE_EXTENSION, dictDirPathBufSize, dictPath)) {
+                AKLOGE("Dictionary file name is not valid as a ver4 dictionary. path: %s", path);
+                ASSERT(false);
+                return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
+            }
+            const Ver4DictBuffers::Ver4DictBuffersPtr dictBuffers =
+                    Ver4DictBuffers::openVer4DictBuffers(dictPath, mmappedBuffer);
+            if (!dictBuffers.get()->isValid()) {
+                AKLOGE("DICT: The dictionary doesn't satisfy ver4 format requirements. path: %s",
+                        path);
+                ASSERT(false);
+                return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
+            }
+            return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(
+                    new Ver4PatriciaTriePolicy(dictBuffers));
+        }
+        default:
+            AKLOGE("DICT: dictionary format is unknown, bad magic number. path: %s", path);
+            break;
+    }
+    ASSERT(false);
+    return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
+}
+
+/* static */ DictionaryStructureWithBufferPolicy::StructurePolicyPtr
+        DictionaryStructureWithBufferPolicyFactory::newPolicyforFileDict(
+                const char *const path, const int bufOffset, const int size) {
+    // Allocated buffer in MmapedBuffer::openBuffer() will be freed in the destructor of
+    // MmappedBufferPtr if the instance has the responsibility.
+    MmappedBuffer::MmappedBufferPtr mmappedBuffer = MmappedBuffer::openBuffer(path, bufOffset,
+            size, false /* isUpdatable */);
+    if (!mmappedBuffer.get()) {
+        return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
+    }
+    switch (FormatUtils::detectFormatVersion(mmappedBuffer.get()->getBuffer(),
+            mmappedBuffer.get()->getBufferSize())) {
+        case FormatUtils::VERSION_2:
             return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(
                     new PatriciaTriePolicy(mmappedBuffer));
-        case FormatUtils::VERSION_4: {
-            const int dictDirPathBufSize = strlen(path) + 1 /* terminator */;
-            char dictDirPath[dictDirPathBufSize];
-            if (!FileUtils::getFilePathWithoutSuffix(path, Ver4DictConstants::HEADER_FILE_EXTENSION,
-                    dictDirPathBufSize, dictDirPath)) {
-                // Dictionary file name is not valid as a version 4 dictionary.
-                return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
-            }
-            const Ver4DictBuffers::Ver4DictBuffersPtr dictBuffers =
-                    Ver4DictBuffers::openVer4DictBuffers(dictDirPath, mmappedBuffer);
-            if (!dictBuffers.get()->isValid()) {
-                AKLOGE("DICT: The dictionary doesn't satisfy ver4 format requirements.");
-                ASSERT(false);
-                return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
-            }
-            return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(
-                    new Ver4PatriciaTriePolicy(dictBuffers));
-        }
+        case FormatUtils::VERSION_4:
+            AKLOGE("Given path is a file but the format is version 4. path: %s", path);
+            break;
         default:
-            AKLOGE("DICT: dictionary format is unknown, bad magic number");
-            ASSERT(false);
-            return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
+            AKLOGE("DICT: dictionary format is unknown, bad magic number. path: %s", path);
+            break;
     }
+    ASSERT(false);
+    return DictionaryStructureWithBufferPolicy::StructurePolicyPtr(0);
+}
+
+/* static */ void DictionaryStructureWithBufferPolicyFactory::getHeaderFilePathInDictDir(
+        const char *const dictDirPath, const int outHeaderFileBufSize,
+        char *const outHeaderFilePath) {
+    const int dictNameBufSize = strlen(dictDirPath) + 1 /* terminator */;
+    char dictName[dictNameBufSize];
+    FileUtils::getBasename(dictDirPath, dictNameBufSize, dictName);
+    snprintf(outHeaderFilePath, outHeaderFileBufSize, "%s/%s%s", dictDirPath,
+            dictName, Ver4DictConstants::HEADER_FILE_EXTENSION);
 }
 
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.h b/native/jni/src/suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.h
index 45237e4..45ab529 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/dictionary_structure_with_buffer_policy_factory.h
@@ -33,6 +33,15 @@
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DictionaryStructureWithBufferPolicyFactory);
+
+    static DictionaryStructureWithBufferPolicy::StructurePolicyPtr
+            newPolicyforDirectoryDict(const char *const path, const bool isUpdatable);
+
+    static DictionaryStructureWithBufferPolicy::StructurePolicyPtr
+            newPolicyforFileDict(const char *const path, const int bufOffset, const int size);
+
+    static void getHeaderFilePathInDictDir(const char *const dirPath,
+            const int outHeaderFileBufSize, char *const outHeaderFilePath);
 };
 } // namespace latinime
 #endif // LATINIME_DICTIONARY_STRUCTURE_WITH_BUFFER_POLICY_FACTORY_H
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.h
index 95ee74f..ba2a052 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/bigram_dict_content.h
@@ -27,9 +27,9 @@
 
 class BigramDictContent : public SparseTableDictContent {
  public:
-    BigramDictContent(const char *const dictDirPath, const bool hasHistoricalInfo,
+    BigramDictContent(const char *const dictPath, const bool hasHistoricalInfo,
             const bool isUpdatable)
-            : SparseTableDictContent(dictDirPath,
+            : SparseTableDictContent(dictPath,
                       Ver4DictConstants::BIGRAM_LOOKUP_TABLE_FILE_EXTENSION,
                       Ver4DictConstants::BIGRAM_CONTENT_TABLE_FILE_EXTENSION,
                       Ver4DictConstants::BIGRAM_FILE_EXTENSION, isUpdatable,
@@ -73,8 +73,8 @@
 
     bool copyBigramList(const int bigramListPos, const int toPos);
 
-    bool flushToFile(const char *const dictBasePath) const {
-        return flush(dictBasePath, Ver4DictConstants::BIGRAM_LOOKUP_TABLE_FILE_EXTENSION,
+    bool flushToFile(const char *const dictPath) const {
+        return flush(dictPath, Ver4DictConstants::BIGRAM_LOOKUP_TABLE_FILE_EXTENSION,
                 Ver4DictConstants::BIGRAM_CONTENT_TABLE_FILE_EXTENSION,
                 Ver4DictConstants::BIGRAM_FILE_EXTENSION);
     }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.cpp
index 749e3fe..3b7c70e 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.cpp
@@ -71,7 +71,7 @@
     return writeEntry(probabilityEntry, entryPos);
 }
 
-bool ProbabilityDictContent::flushToFile(const char *const dictBasePath) const {
+bool ProbabilityDictContent::flushToFile(const char *const dictPath) const {
     if (getEntryPos(mSize) < getBuffer()->getTailPosition()) {
         ProbabilityDictContent probabilityDictContentToWrite(mHasHistoricalInfo);
         for (int i = 0; i < mSize; ++i) {
@@ -81,10 +81,10 @@
                 return false;
             }
         }
-        return probabilityDictContentToWrite.flush(dictBasePath,
+        return probabilityDictContentToWrite.flush(dictPath,
                 Ver4DictConstants::FREQ_FILE_EXTENSION);
     } else {
-        return flush(dictBasePath, Ver4DictConstants::FREQ_FILE_EXTENSION);
+        return flush(dictPath, Ver4DictConstants::FREQ_FILE_EXTENSION);
     }
 }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h
index db96f90..b065bc9 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/probability_dict_content.h
@@ -29,9 +29,9 @@
 
 class ProbabilityDictContent : public SingleDictContent {
  public:
-    ProbabilityDictContent(const char *const dictDirPath, const bool hasHistoricalInfo,
+    ProbabilityDictContent(const char *const dictPath, const bool hasHistoricalInfo,
             const bool isUpdatable)
-            : SingleDictContent(dictDirPath, Ver4DictConstants::FREQ_FILE_EXTENSION, isUpdatable),
+            : SingleDictContent(dictPath, Ver4DictConstants::FREQ_FILE_EXTENSION, isUpdatable),
               mHasHistoricalInfo(hasHistoricalInfo),
               mSize(getBuffer()->getTailPosition() / getEntrySize()) {}
 
@@ -42,7 +42,7 @@
 
     bool setProbabilityEntry(const int terminalId, const ProbabilityEntry *const probabilityEntry);
 
-    bool flushToFile(const char *const dictDirPath) const;
+    bool flushToFile(const char *const dictPath) const;
 
     bool runGC(const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
             const ProbabilityDictContent *const originalProbabilityDictContent);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
index 5552178..29972a4 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.cpp
@@ -46,8 +46,8 @@
     return addressLookupTable->get(terminalId);
 }
 
-bool ShortcutDictContent::flushToFile(const char *const dictBasePath) const {
-    return flush(dictBasePath, Ver4DictConstants::SHORTCUT_LOOKUP_TABLE_FILE_EXTENSION,
+bool ShortcutDictContent::flushToFile(const char *const dictPath) const {
+    return flush(dictPath, Ver4DictConstants::SHORTCUT_LOOKUP_TABLE_FILE_EXTENSION,
             Ver4DictConstants::SHORTCUT_CONTENT_TABLE_FILE_EXTENSION,
             Ver4DictConstants::SHORTCUT_FILE_EXTENSION);
 }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.h
index a52214c..eaafc27 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/shortcut_dict_content.h
@@ -26,8 +26,8 @@
 
 class ShortcutDictContent : public SparseTableDictContent {
  public:
-    ShortcutDictContent(const char *const dictDirPath, const bool isUpdatable)
-            : SparseTableDictContent(dictDirPath,
+    ShortcutDictContent(const char *const dictPath, const bool isUpdatable)
+            : SparseTableDictContent(dictPath,
                       Ver4DictConstants::SHORTCUT_LOOKUP_TABLE_FILE_EXTENSION,
                       Ver4DictConstants::SHORTCUT_CONTENT_TABLE_FILE_EXTENSION,
                       Ver4DictConstants::SHORTCUT_FILE_EXTENSION, isUpdatable,
@@ -53,7 +53,7 @@
    // Returns head position of shortcut list for a PtNode specified by terminalId.
    int getShortcutListHeadPos(const int terminalId) const;
 
-   bool flushToFile(const char *const dictBasePath) const;
+   bool flushToFile(const char *const dictPath) const;
 
    bool runGC(const TerminalPositionLookupTable::TerminalIdMap *const terminalIdMap,
            const ShortcutDictContent *const originalShortcutDictContent);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/single_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/single_dict_content.h
index d8eedf3..9064b7e 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/single_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/single_dict_content.h
@@ -28,9 +28,9 @@
 
 class SingleDictContent : public DictContent {
  public:
-    SingleDictContent(const char *const dictDirPath, const char *const contentFileName,
+    SingleDictContent(const char *const dictPath, const char *const contentFileName,
             const bool isUpdatable)
-            : mMmappedBuffer(MmappedBuffer::openBuffer(dictDirPath, contentFileName, isUpdatable)),
+            : mMmappedBuffer(MmappedBuffer::openBuffer(dictPath, contentFileName, isUpdatable)),
               mExpandableContentBuffer(mMmappedBuffer.get() ? mMmappedBuffer.get()->getBuffer() : 0,
                       mMmappedBuffer.get() ? mMmappedBuffer.get()->getBufferSize() : 0,
                       BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE),
@@ -59,8 +59,8 @@
         return &mExpandableContentBuffer;
     }
 
-    bool flush(const char *const dictBasePath, const char *const contentFileNameSuffix) const {
-        return DictFileWritingUtils::flushBufferToFileWithSuffix(dictBasePath,
+    bool flush(const char *const dictPath, const char *const contentFileNameSuffix) const {
+        return DictFileWritingUtils::flushBufferToFileWithSuffix(dictPath,
                 contentFileNameSuffix, &mExpandableContentBuffer);
     }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.cpp
index abb7d5f..63c6ea3 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.cpp
@@ -18,18 +18,18 @@
 
 namespace latinime {
 
-bool SparseTableDictContent::flush(const char *const dictBasePath,
+bool SparseTableDictContent::flush(const char *const dictPath,
         const char *const lookupTableFileNameSuffix, const char *const addressTableFileNameSuffix,
         const char *const contentFileNameSuffix) const {
-    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictBasePath, lookupTableFileNameSuffix,
+    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictPath, lookupTableFileNameSuffix,
             &mExpandableLookupTableBuffer)){
         return false;
     }
-    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictBasePath, addressTableFileNameSuffix,
+    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictPath, addressTableFileNameSuffix,
             &mExpandableAddressTableBuffer)) {
         return false;
     }
-    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictBasePath, contentFileNameSuffix,
+    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictPath, contentFileNameSuffix,
             &mExpandableContentBuffer)) {
         return false;
     }
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h
index 9a4f1e1..a82e3f5 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/sparse_table_dict_content.h
@@ -30,15 +30,15 @@
 // TODO: Support multiple contents.
 class SparseTableDictContent : public DictContent {
  public:
-    AK_FORCE_INLINE SparseTableDictContent(const char *const dictDirPath,
+    AK_FORCE_INLINE SparseTableDictContent(const char *const dictPath,
             const char *const lookupTableFileName, const char *const addressTableFileName,
             const char *const contentFileName, const bool isUpdatable,
             const int sparseTableBlockSize, const int sparseTableDataSize)
             : mLookupTableBuffer(
-                      MmappedBuffer::openBuffer(dictDirPath, lookupTableFileName, isUpdatable)),
+                      MmappedBuffer::openBuffer(dictPath, lookupTableFileName, isUpdatable)),
               mAddressTableBuffer(
-                      MmappedBuffer::openBuffer(dictDirPath, addressTableFileName, isUpdatable)),
-              mContentBuffer(MmappedBuffer::openBuffer(dictDirPath, contentFileName, isUpdatable)),
+                      MmappedBuffer::openBuffer(dictPath, addressTableFileName, isUpdatable)),
+              mContentBuffer(MmappedBuffer::openBuffer(dictPath, contentFileName, isUpdatable)),
               mExpandableLookupTableBuffer(
                       mLookupTableBuffer.get() ? mLookupTableBuffer.get()->getBuffer() : 0,
                       mLookupTableBuffer.get() ? mLookupTableBuffer.get()->getBufferSize() : 0,
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.cpp
index c889cf5..0b17a00 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.cpp
@@ -50,7 +50,7 @@
             Ver4DictConstants::TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE, getEntryPos(terminalId));
 }
 
-bool TerminalPositionLookupTable::flushToFile(const char *const dictBasePath) const {
+bool TerminalPositionLookupTable::flushToFile(const char *const dictPath) const {
     // If the used buffer size is smaller than the actual buffer size, regenerate the lookup
     // table and write the new table to the file.
     if (getEntryPos(mSize) < getBuffer()->getTailPosition()) {
@@ -63,12 +63,12 @@
                 return false;
             }
         }
-        return lookupTableToWrite.flush(dictBasePath,
+        return lookupTableToWrite.flush(dictPath,
                 Ver4DictConstants::TERMINAL_ADDRESS_TABLE_FILE_EXTENSION);
     } else {
         // We can simply use this lookup table because the buffer size has not been
         // changed.
-        return flush(dictBasePath, Ver4DictConstants::TERMINAL_ADDRESS_TABLE_FILE_EXTENSION);
+        return flush(dictPath, Ver4DictConstants::TERMINAL_ADDRESS_TABLE_FILE_EXTENSION);
     }
 }
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h
index 5a28f52..f73e227 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/content/terminal_position_lookup_table.h
@@ -28,8 +28,8 @@
  public:
     typedef hash_map_compat<int, int> TerminalIdMap;
 
-    TerminalPositionLookupTable(const char *const dictDirPath, const bool isUpdatable)
-            : SingleDictContent(dictDirPath,
+    TerminalPositionLookupTable(const char *const dictPath, const bool isUpdatable)
+            : SingleDictContent(dictPath,
                       Ver4DictConstants::TERMINAL_ADDRESS_TABLE_FILE_EXTENSION, isUpdatable),
               mSize(getBuffer()->getTailPosition()
                       / Ver4DictConstants::TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE) {}
@@ -44,7 +44,7 @@
         return mSize;
     }
 
-    bool flushToFile(const char *const dictBasePath) const;
+    bool flushToFile(const char *const dictPath) const;
 
     bool runGCTerminalIds(TerminalIdMap *const terminalIdMap);
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.cpp
index e235540..918c02b 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_dict_buffers.cpp
@@ -27,10 +27,10 @@
 namespace latinime {
 
 /* static */ Ver4DictBuffers::Ver4DictBuffersPtr Ver4DictBuffers::openVer4DictBuffers(
-        const char *const dictDirPath, const MmappedBuffer::MmappedBufferPtr &headerBuffer) {
+        const char *const dictPath, const MmappedBuffer::MmappedBufferPtr &headerBuffer) {
     const bool isUpdatable = headerBuffer.get() ? headerBuffer.get()->isUpdatable() : false;
     // TODO: take only dictDirPath, and open both header and trie files in the constructor below
-    return Ver4DictBuffersPtr(new Ver4DictBuffers(dictDirPath, headerBuffer, isUpdatable));
+    return Ver4DictBuffersPtr(new Ver4DictBuffers(dictPath, headerBuffer, isUpdatable));
 }
 
 bool Ver4DictBuffers::flushHeaderAndDictBuffers(const char *const dictDirPath,
@@ -57,38 +57,38 @@
     const int dictNameBufSize = strlen(dictDirPath) + 1 /* terminator */;
     char dictName[dictNameBufSize];
     FileUtils::getBasename(dictDirPath, dictNameBufSize, dictName);
-    const int dictBasePathBufSize = FileUtils::getFilePathBufSize(tmpDirPath, dictName);
-    char dictBasePath[dictBasePathBufSize];
-    FileUtils::getFilePath(tmpDirPath, dictName, dictBasePathBufSize, dictBasePath);
+    const int dictPathBufSize = FileUtils::getFilePathBufSize(tmpDirPath, dictName);
+    char dictPath[dictPathBufSize];
+    FileUtils::getFilePath(tmpDirPath, dictName, dictPathBufSize, dictPath);
 
     // Write header file.
-    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictBasePath,
+    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictPath,
             Ver4DictConstants::HEADER_FILE_EXTENSION, headerBuffer)) {
         AKLOGE("Dictionary header file %s%s cannot be written.", tmpDirPath,
                 Ver4DictConstants::HEADER_FILE_EXTENSION);
         return false;
     }
     // Write trie file.
-    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictBasePath,
+    if (!DictFileWritingUtils::flushBufferToFileWithSuffix(dictPath,
             Ver4DictConstants::TRIE_FILE_EXTENSION, &mExpandableTrieBuffer)) {
         AKLOGE("Dictionary trie file %s%s cannot be written.", tmpDirPath,
                 Ver4DictConstants::TRIE_FILE_EXTENSION);
         return false;
     }
     // Write dictionary contents.
-    if (!mTerminalPositionLookupTable.flushToFile(dictBasePath)) {
+    if (!mTerminalPositionLookupTable.flushToFile(dictPath)) {
         AKLOGE("Terminal position lookup table cannot be written. %s", tmpDirPath);
         return false;
     }
-    if (!mProbabilityDictContent.flushToFile(dictBasePath)) {
+    if (!mProbabilityDictContent.flushToFile(dictPath)) {
         AKLOGE("Probability dict content cannot be written. %s", tmpDirPath);
         return false;
     }
-    if (!mBigramDictContent.flushToFile(dictBasePath)) {
+    if (!mBigramDictContent.flushToFile(dictPath)) {
         AKLOGE("Bigram dict content cannot be written. %s", tmpDirPath);
         return false;
     }
-    if (!mShortcutDictContent.flushToFile(dictBasePath)) {
+    if (!mShortcutDictContent.flushToFile(dictPath)) {
         AKLOGE("Shortcut dict content cannot be written. %s", tmpDirPath);
         return false;
     }
@@ -107,10 +107,10 @@
     return true;
 }
 
-Ver4DictBuffers::Ver4DictBuffers(const char *const dictDirPath,
+Ver4DictBuffers::Ver4DictBuffers(const char *const dictPath,
         const MmappedBuffer::MmappedBufferPtr &headerBuffer, const bool isUpdatable)
         : mHeaderBuffer(headerBuffer),
-          mDictBuffer(MmappedBuffer::openBuffer(dictDirPath,
+          mDictBuffer(MmappedBuffer::openBuffer(dictPath,
                   Ver4DictConstants::TRIE_FILE_EXTENSION, isUpdatable)),
           mHeaderPolicy(headerBuffer.get()->getBuffer(), FormatUtils::VERSION_4),
           mExpandableHeaderBuffer(headerBuffer.get()->getBuffer(), mHeaderPolicy.getSize(),
@@ -118,12 +118,12 @@
           mExpandableTrieBuffer(mDictBuffer.get()->getBuffer(),
                   mDictBuffer.get()->getBufferSize(),
                   BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE),
-          mTerminalPositionLookupTable(dictDirPath, isUpdatable),
-          mProbabilityDictContent(dictDirPath, mHeaderPolicy.hasHistoricalInfoOfWords(),
+          mTerminalPositionLookupTable(dictPath, isUpdatable),
+          mProbabilityDictContent(dictPath, mHeaderPolicy.hasHistoricalInfoOfWords(),
                   isUpdatable),
-          mBigramDictContent(dictDirPath, mHeaderPolicy.hasHistoricalInfoOfWords(),
+          mBigramDictContent(dictPath, mHeaderPolicy.hasHistoricalInfoOfWords(),
                   isUpdatable),
-          mShortcutDictContent(dictDirPath, isUpdatable),
+          mShortcutDictContent(dictPath, isUpdatable),
           mIsUpdatable(isUpdatable) {}
 
 Ver4DictBuffers::Ver4DictBuffers(const HeaderPolicy *const headerPolicy)
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
index 25f87ef..4322763 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
@@ -32,12 +32,9 @@
 
 namespace latinime {
 
-void Ver4PatriciaTrieWritingHelper::writeToDictFile(const char *const trieFilePath,
+void Ver4PatriciaTrieWritingHelper::writeToDictFile(const char *const dictDirPath,
         const int unigramCount, const int bigramCount) const {
     const HeaderPolicy *const headerPolicy = mBuffers->getHeaderPolicy();
-    const int dirPathBufSize = strlen(trieFilePath) + 1 /* terminator */;
-    char dirPath[dirPathBufSize];
-    FileUtils::getDirPath(trieFilePath, dirPathBufSize, dirPath);
     BufferWithExtendableBuffer headerBuffer(
             BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE);
     const int extendedRegionSize = headerPolicy->getExtendedRegionSize()
@@ -50,11 +47,11 @@
                 extendedRegionSize);
         return;
     }
-    mBuffers->flushHeaderAndDictBuffers(dirPath, &headerBuffer);
+    mBuffers->flushHeaderAndDictBuffers(dictDirPath, &headerBuffer);
 }
 
 void Ver4PatriciaTrieWritingHelper::writeToDictFileWithGC(const int rootPtNodeArrayPos,
-        const char *const trieFilePath) {
+        const char *const dictDirPath) {
     const HeaderPolicy *const headerPolicy = mBuffers->getHeaderPolicy();
     Ver4DictBuffers::Ver4DictBuffersPtr dictBuffers(
             Ver4DictBuffers::createVer4DictBuffers(headerPolicy));
@@ -70,10 +67,7 @@
             0 /* extendedRegionSize */)) {
         return;
     }
-    const int dirPathBufSize = strlen(trieFilePath) + 1 /* terminator */;
-    char dirPath[dirPathBufSize];
-    FileUtils::getDirPath(trieFilePath, dirPathBufSize, dirPath);
-    dictBuffers.get()->flushHeaderAndDictBuffers(dirPath, &headerBuffer);
+    dictBuffers.get()->flushHeaderAndDictBuffers(dictDirPath, &headerBuffer);
 }
 
 bool Ver4PatriciaTrieWritingHelper::runGC(const int rootPtNodeArrayPos,
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
index 198c108..c3a155e 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
@@ -33,11 +33,10 @@
     Ver4PatriciaTrieWritingHelper(Ver4DictBuffers *const buffers)
             : mBuffers(buffers) {}
 
-    void writeToDictFile(const char *const trieFilePath, const int unigramCount,
+    void writeToDictFile(const char *const dictDirPath, const int unigramCount,
             const int bigramCount) const;
 
-    void writeToDictFileWithGC(const int rootPtNodeArrayPos,
-            const char *const trieFilePath);
+    void writeToDictFileWithGC(const int rootPtNodeArrayPos, const char *const dictDirPath);
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4PatriciaTrieWritingHelper);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/file_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/utils/file_utils.cpp
index 49ae7f1..1f25cfa 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/file_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/file_utils.cpp
@@ -147,7 +147,7 @@
     const char *const baseName = basename(filePathBuf);
     const int baseNameLength = strlen(baseName);
     if (baseNameLength >= outNameBufSize) {
-        AKLOGE("outNameBufSize is too small. dirPath: %s, outNameBufSize: %d",
+        AKLOGE("outNameBufSize is too small. filePath: %s, outNameBufSize: %d",
                 filePath, outNameBufSize);
         return;
     }
diff --git a/native/jni/src/utils/exclusive_ownership_pointer.h b/native/jni/src/utils/exclusive_ownership_pointer.h
index 617b349..081802e 100644
--- a/native/jni/src/utils/exclusive_ownership_pointer.h
+++ b/native/jni/src/utils/exclusive_ownership_pointer.h
@@ -39,25 +39,15 @@
         deletePointersIfHavingOwnership();
     }
 
-    // Move the ownership.
-    AK_FORCE_INLINE ExclusiveOwnershipPointer<T> &operator=(
-            const ExclusiveOwnershipPointer<T> &pointer) {
-        // Delete pointers when this is an owner of another pointer.
-        deletePointersIfHavingOwnership();
-        mPointer = pointer.mPointer;
-        mSharedOwnerPtr = pointer.mSharedOwnerPtr;
-        transferOwnership(pointer);
-        return *this;
-    }
-
     AK_FORCE_INLINE T *get() const {
         return mPointer;
     }
 
  private:
-    // This class allows to copy and assign and ensures only one instance has the ownership of the
+    // This class allows to copy and ensures only one instance has the ownership of the
     // managed pointer.
     DISALLOW_DEFAULT_CONSTRUCTOR(ExclusiveOwnershipPointer);
+    DISALLOW_ASSIGNMENT_OPERATOR(ExclusiveOwnershipPointer);
 
     void transferOwnership(const ExclusiveOwnershipPointer<T> *const src) {
         if (*mSharedOwnerPtr != src) {
diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
index 931ba7d..e027651 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
@@ -114,7 +114,6 @@
         final File file = File.createTempFile(dictId, TEST_DICT_FILE_EXTENSION,
                 getContext().getCacheDir());
         FileUtils.deleteRecursively(file);
-        file.mkdir();
         Map<String, String> attributeMap = new HashMap<String, String>();
         attributeMap.put(FormatSpec.FileHeader.SUPPORTS_DYNAMIC_UPDATE_ATTRIBUTE,
                 FormatSpec.FileHeader.ATTRIBUTE_VALUE_TRUE);
@@ -125,7 +124,7 @@
         final String headerFileName = file.getName() + FormatSpec.HEADER_FILE_EXTENSION;
         if (BinaryDictionary.createEmptyDictFile(file.getAbsolutePath(),
                 FormatSpec.VERSION4, attributeMap)) {
-            return new File(file, headerFileName);
+            return file;
         } else {
             throw new IOException("Empty dictionary " + file.getAbsolutePath() + " "
                     + headerFileName + " cannot be created.");
diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
index d9d4a55..cfc4c76 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
@@ -25,6 +25,7 @@
 import com.android.inputmethod.latin.makedict.CodePointUtils;
 import com.android.inputmethod.latin.makedict.FormatSpec;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
+import com.android.inputmethod.latin.utils.FileUtils;
 import com.android.inputmethod.latin.utils.UnigramProperty;
 
 import java.io.File;
@@ -70,13 +71,12 @@
         Map<String, String> attributeMap = new HashMap<String, String>();
         attributeMap.put(FormatSpec.FileHeader.SUPPORTS_DYNAMIC_UPDATE_ATTRIBUTE,
                 FormatSpec.FileHeader.ATTRIBUTE_VALUE_TRUE);
-        final String headerFileName = file.getName() + FormatSpec.HEADER_FILE_EXTENSION;
         if (BinaryDictionary.createEmptyDictFile(file.getAbsolutePath(),
                 FormatSpec.VERSION4, attributeMap)) {
-            return new File(file, headerFileName);
+            return file;
         } else {
-            throw new IOException("Empty dictionary " + file.getAbsolutePath() + " "
-                    + headerFileName + " cannot be created.");
+            throw new IOException("Empty dictionary " + file.getAbsolutePath()
+                    + " cannot be created.");
         }
     }
 
@@ -99,7 +99,7 @@
         binaryDictionary.close();
         assertFalse("binaryDictionary must be invalid after closing.",
                 binaryDictionary.isValidDictionary());
-        dictFile.delete();
+        FileUtils.deleteRecursively(dictFile);
         binaryDictionary = new BinaryDictionary(dictFile.getAbsolutePath(), 0 /* offset */,
                 dictFile.length(), true /* useFullEditDistance */, Locale.getDefault(),
                 TEST_LOCALE, true /* isUpdatable */);
diff --git a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
index f0fe3f2..68e94c8 100644
--- a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
@@ -20,6 +20,7 @@
 import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Log;
 
+import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 import com.android.inputmethod.latin.utils.CollectionUtils;
 
 import java.io.File;
@@ -136,7 +137,8 @@
         Log.d(TAG, "This test can be used for profiling.");
         Log.d(TAG, "Usage: please set UserHistoryDictionary.PROFILE_SAVE_RESTORE to true.");
         final String testFilenameSuffix = "test_random_words" + System.currentTimeMillis();
-        final String fileName = UserHistoryDictionary.NAME + "." + testFilenameSuffix;
+        final String fileName = UserHistoryDictionary.NAME + "." + testFilenameSuffix
+                + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
 
         final int numberOfWords = 1000;
         final Random random = new Random(123456);
@@ -151,7 +153,6 @@
             final File dictFile = new File(getContext().getFilesDir(), fileName);
             if (dictFile != null) {
                 assertTrue(dictFile.exists());
-                assertTrue(dictFile.length() >= MIN_USER_HISTORY_DICTIONARY_FILE_SIZE);
                 dictFile.delete();
             }
         }
@@ -170,7 +171,8 @@
             // Create filename suffixes for this test.
             for (int i = 0; i < numberOfLanguages; i++) {
                 testFilenameSuffixes[i] = "test_switching_languages" + i;
-                final String fileName = UserHistoryDictionary.NAME + "." + testFilenameSuffixes[i];
+                final String fileName = UserHistoryDictionary.NAME + "." + testFilenameSuffixes[i]
+                        + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
                 dictFiles[i] = new File(getContext().getFilesDir(), fileName);
                 clearHistory(testFilenameSuffixes[i]);
             }
@@ -196,7 +198,6 @@
             for (final File file : dictFiles) {
                 if (file != null) {
                     assertTrue(file.exists());
-                    assertTrue(file.length() >= MIN_USER_HISTORY_DICTIONARY_FILE_SIZE);
                     file.delete();
                 }
             }
@@ -214,11 +215,11 @@
         } finally {
             Log.d(TAG, "waiting for writing ...");
             waitForWriting(testFilenameSuffix);
-            final String fileName = UserHistoryDictionary.NAME + "." + testFilenameSuffix;
+            final String fileName = UserHistoryDictionary.NAME + "." + testFilenameSuffix
+                    + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
             final File dictFile = new File(getContext().getFilesDir(), fileName);
             if (dictFile != null) {
                 assertTrue(dictFile.exists());
-                assertTrue(dictFile.length() >= MIN_USER_HISTORY_DICTIONARY_FILE_SIZE);
                 dictFile.delete();
             }
         }