diff --git a/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java b/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
index 8a8a45f..8b02984 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryFacilitatorForSuggest.java
@@ -505,6 +505,14 @@
         }
     }
 
+    @UsedForTesting
+    public void clearUserHistoryDictionary() {
+        if (mUserHistoryDictionary == null) {
+            return;
+        }
+        mUserHistoryDictionary.clearAndFlushDictionary();
+    }
+
     // This method gets called only when the IME receives a notification to remove the
     // personalization dictionary.
     public void clearPersonalizationDictionary() {
diff --git a/java/src/com/android/inputmethod/latin/makedict/AbstractDictDecoder.java b/java/src/com/android/inputmethod/latin/makedict/AbstractDictDecoder.java
index f8fa68f..370782b 100644
--- a/java/src/com/android/inputmethod/latin/makedict/AbstractDictDecoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/AbstractDictDecoder.java
@@ -48,7 +48,7 @@
           throw new UnsupportedFormatException("Unsupported version : " + version);
         }
         // TODO: Remove this field.
-        final int optionsFlags = HeaderReader.readOptionFlags(headerBuffer);
+        HeaderReader.readOptionFlags(headerBuffer);
         final int headerSize = HeaderReader.readHeaderSize(headerBuffer);
         if (headerSize < 0) {
             throw new UnsupportedFormatException("header size can't be negative.");
@@ -59,8 +59,8 @@
 
         final FileHeader header = new FileHeader(headerSize,
                 new FusionDictionary.DictionaryOptions(attributes),
-                new FormatOptions(version,
-                        0 != (optionsFlags & FormatSpec.CONTAINS_TIMESTAMP_FLAG)));
+                new FormatOptions(version, FileHeader.ATTRIBUTE_VALUE_TRUE.equals(
+                        attributes.get(FileHeader.HAS_HISTORICAL_INFO_ATTRIBUTE))));
         return header;
     }
 
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderUtils.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderUtils.java
index 9a24c47..3174715 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderUtils.java
@@ -499,7 +499,6 @@
         final int nodeArrayOriginPos = dictDecoder.getPosition();
 
         do { // Scan the linked-list node.
-            final int nodeArrayHeadPos = dictDecoder.getPosition();
             final int count = dictDecoder.readPtNodeCount();
             int groupPos = dictDecoder.getPosition();
             for (int i = count; i > 0; --i) { // Scan the array of PtNode.
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoderUtils.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoderUtils.java
index bb40e0d..eff8fc3 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoderUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoderUtils.java
@@ -756,14 +756,6 @@
     }
 
     /**
-     * Makes the 2-byte value for options flags. Unused at the moment, and always 0.
-     */
-    private static final int makeOptionsValue(final FormatOptions formatOptions) {
-        // TODO: why doesn't this handle CONTAINS_TIMESTAMP_FLAG?
-        return 0;
-    }
-
-    /**
      * Makes the flag value for a shortcut.
      *
      * @param more whether there are more attributes after this one.
@@ -949,7 +941,8 @@
         headerBuffer.write((byte) (0xFF & version));
 
         // Options flags
-        final int options = makeOptionsValue(formatOptions);
+        // TODO: Remove this field.
+        final int options = 0;
         headerBuffer.write((byte) (0xFF & (options >> 8)));
         headerBuffer.write((byte) (0xFF & options));
         final int headerSizeOffset = headerBuffer.size();
diff --git a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
index 437fa94..61c17fc 100644
--- a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
+++ b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
@@ -192,10 +192,6 @@
     static final int MINIMUM_SUPPORTED_VERSION = VERSION2;
     static final int MAXIMUM_SUPPORTED_VERSION = VERSION4;
 
-    // These options need to be the same numeric values as the one in the native reading code.
-    // TODO: Make the native reading code read this variable.
-    static final int CONTAINS_TIMESTAMP_FLAG = 0x10;
-
     // TODO: Make this value adaptative to content data, store it in the header, and
     // use it in the reading code.
     static final int MAX_WORD_LENGTH = Constants.DICTIONARY_MAX_WORD_LENGTH;
@@ -249,26 +245,26 @@
     static final String TRIE_FILE_EXTENSION = ".trie";
     public static final String HEADER_FILE_EXTENSION = ".header";
     static final String FREQ_FILE_EXTENSION = ".freq";
-    static final String UNIGRAM_TIMESTAMP_FILE_EXTENSION = ".timestamp";
     // tat = Terminal Address Table
     static final String TERMINAL_ADDRESS_TABLE_FILE_EXTENSION = ".tat";
     static final String BIGRAM_FILE_EXTENSION = ".bigram";
     static final String SHORTCUT_FILE_EXTENSION = ".shortcut";
     static final String LOOKUP_TABLE_FILE_SUFFIX = "_lookup";
     static final String CONTENT_TABLE_FILE_SUFFIX = "_index";
+    static final int FLAGS_IN_FREQ_FILE_SIZE = 1;
     static final int FREQUENCY_AND_FLAGS_SIZE = 2;
     static final int TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE = 3;
     static final int UNIGRAM_TIMESTAMP_SIZE = 4;
+    static final int UNIGRAM_COUNTER_SIZE = 1;
+    static final int UNIGRAM_LEVEL_SIZE = 1;
 
     // With the English main dictionary as of October 2013, the size of bigram address table is
     // is 345KB with the block size being 16.
     // This is 54% of that of full address table.
     static final int BIGRAM_ADDRESS_TABLE_BLOCK_SIZE = 16;
-    static final int BIGRAM_CONTENT_COUNT = 2;
+    static final int BIGRAM_CONTENT_COUNT = 1;
     static final int BIGRAM_FREQ_CONTENT_INDEX = 0;
-    static final int BIGRAM_TIMESTAMP_CONTENT_INDEX = 1;
     static final String BIGRAM_FREQ_CONTENT_ID = "_freq";
-    static final String BIGRAM_TIMESTAMP_CONTENT_ID = "_timestamp";
     static final int BIGRAM_TIMESTAMP_SIZE = 4;
     static final int BIGRAM_COUNTER_SIZE = 1;
     static final int BIGRAM_LEVEL_SIZE = 1;
diff --git a/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java b/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
index fdf2ae7..5b0e839 100644
--- a/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
+++ b/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
@@ -61,6 +61,7 @@
             mData = new ArrayList<PtNode>();
         }
         public PtNodeArray(ArrayList<PtNode> data) {
+            Collections.sort(data, PTNODE_COMPARATOR);
             mData = data;
         }
     }
diff --git a/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java b/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
index 7071893..f230229 100644
--- a/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
@@ -143,7 +143,7 @@
         mTerminalAddressTableBuffer = mBufferFactory.getDictionaryBuffer(
                 getFile(FILETYPE_TERMINAL_ADDRESS_TABLE));
         mBigramReader = new BigramContentReader(mDictDirectory.getName(),
-                mDictDirectory, mBufferFactory, false);
+                mDictDirectory, mBufferFactory);
         mBigramReader.openBuffers();
         mShortcutReader = new ShortcutContentReader(mDictDirectory.getName(), mDictDirectory,
                 mBufferFactory);
@@ -184,39 +184,24 @@
      */
     protected static class BigramContentReader extends SparseTableContentReader {
         public BigramContentReader(final String name, final File baseDir,
-                final DictionaryBufferFactory factory, final boolean hasTimestamp) {
+                final DictionaryBufferFactory factory) {
             super(name + FormatSpec.BIGRAM_FILE_EXTENSION,
                     FormatSpec.BIGRAM_ADDRESS_TABLE_BLOCK_SIZE, baseDir,
-                    getContentFilenames(name, hasTimestamp), getContentIds(hasTimestamp), factory);
+                    getContentFilenames(name), getContentIds(), factory);
         }
 
         // TODO: Consolidate this method and BigramContentWriter.getContentFilenames.
-        protected static String[] getContentFilenames(final String name,
-                final boolean hasTimestamp) {
-            final String[] contentFilenames;
-            if (hasTimestamp) {
-                contentFilenames = new String[] { name + FormatSpec.BIGRAM_FILE_EXTENSION,
-                        name + FormatSpec.BIGRAM_FILE_EXTENSION };
-            } else {
-                contentFilenames = new String[] { name + FormatSpec.BIGRAM_FILE_EXTENSION };
-            }
-            return contentFilenames;
+        protected static String[] getContentFilenames(final String name) {
+            return new String[] { name + FormatSpec.BIGRAM_FILE_EXTENSION };
         }
 
         // TODO: Consolidate this method and BigramContentWriter.getContentIds.
-        protected static String[] getContentIds(final boolean hasTimestamp) {
-            final String[] contentIds;
-            if (hasTimestamp) {
-                contentIds = new String[] { FormatSpec.BIGRAM_FREQ_CONTENT_ID,
-                        FormatSpec.BIGRAM_TIMESTAMP_CONTENT_ID };
-            } else {
-                contentIds = new String[] { FormatSpec.BIGRAM_FREQ_CONTENT_ID };
-            }
-            return contentIds;
+        protected static String[] getContentIds() {
+            return new String[] { FormatSpec.BIGRAM_FREQ_CONTENT_ID };
         }
 
         public ArrayList<PendingAttribute> readTargetsAndFrequencies(final int terminalId,
-                final DictBuffer terminalAddressTableBuffer) {
+                final DictBuffer terminalAddressTableBuffer, final FormatOptions options) {
             final ArrayList<PendingAttribute> bigrams = CollectionUtils.newArrayList();
             read(FormatSpec.BIGRAM_FREQ_CONTENT_INDEX, terminalId,
                     new SparseTableContentReaderInterface() {
@@ -226,14 +211,25 @@
                                 // If bigrams.size() reaches FormatSpec.MAX_BIGRAMS_IN_A_PTNODE,
                                 // remaining bigram entries are ignored.
                                 final int bigramFlags = buffer.readUnsignedByte();
+                                final int probability;
+
+                                if (options.mHasTimestamp) {
+                                    probability = buffer.readUnsignedByte();
+                                    final int pos = buffer.position();
+                                    // Skip historical info.
+                                    buffer.position(pos + FormatSpec.BIGRAM_TIMESTAMP_SIZE
+                                            + FormatSpec.BIGRAM_LEVEL_SIZE
+                                            + FormatSpec.BIGRAM_COUNTER_SIZE);
+                                } else {
+                                    probability = bigramFlags
+                                            & FormatSpec.FLAG_BIGRAM_SHORTCUT_ATTR_FREQUENCY;
+                                }
                                 final int targetTerminalId = buffer.readUnsignedInt24();
                                 terminalAddressTableBuffer.position(targetTerminalId
                                         * FormatSpec.TERMINAL_ADDRESS_TABLE_ADDRESS_SIZE);
                                 final int targetAddress =
                                         terminalAddressTableBuffer.readUnsignedInt24();
-                                bigrams.add(new PendingAttribute(bigramFlags
-                                        & FormatSpec.FLAG_BIGRAM_SHORTCUT_ATTR_FREQUENCY,
-                                        targetAddress));
+                                bigrams.add(new PendingAttribute(probability, targetAddress));
                                 if (0 == (bigramFlags
                                         & FormatSpec.FLAG_BIGRAM_SHORTCUT_ATTR_HAS_NEXT)) {
                                     break;
@@ -286,8 +282,19 @@
     }
 
     protected static class PtNodeReader extends AbstractDictDecoder.PtNodeReader {
-        protected static int readFrequency(final DictBuffer frequencyBuffer, final int terminalId) {
-            frequencyBuffer.position(terminalId * FormatSpec.FREQUENCY_AND_FLAGS_SIZE + 1);
+        protected static int readFrequency(final DictBuffer frequencyBuffer, final int terminalId,
+                final FormatOptions formatOptions) {
+            final int readingPos;
+            if (formatOptions.mHasTimestamp) {
+                final int entrySize = FormatSpec.FREQUENCY_AND_FLAGS_SIZE
+                        + FormatSpec.UNIGRAM_TIMESTAMP_SIZE + FormatSpec.UNIGRAM_LEVEL_SIZE
+                        + FormatSpec.UNIGRAM_COUNTER_SIZE;
+                readingPos = terminalId * entrySize + FormatSpec.FLAGS_IN_FREQ_FILE_SIZE;
+            } else {
+                readingPos = terminalId * FormatSpec.FREQUENCY_AND_FLAGS_SIZE
+                        + FormatSpec.FLAGS_IN_FREQ_FILE_SIZE;
+            }
+            frequencyBuffer.position(readingPos);
             return frequencyBuffer.readUnsignedByte();
         }
 
@@ -354,12 +361,12 @@
     }
 
     @Override
-    public PtNodeInfo readPtNode(int ptNodePos, FormatOptions options) {
+    public PtNodeInfo readPtNode(final int ptNodePos, final FormatOptions options) {
         final Ver4PtNodeInfo nodeInfo = readVer4PtNodeInfo(ptNodePos, options);
 
         final int frequency;
         if (0 != (FormatSpec.FLAG_IS_TERMINAL & nodeInfo.mFlags)) {
-            frequency = PtNodeReader.readFrequency(mFrequencyBuffer, nodeInfo.mTerminalId);
+            frequency = PtNodeReader.readFrequency(mFrequencyBuffer, nodeInfo.mTerminalId, options);
         } else {
             frequency = PtNode.NOT_A_TERMINAL;
         }
@@ -367,7 +374,7 @@
         final ArrayList<WeightedString> shortcutTargets = mShortcutReader.readShortcuts(
                 nodeInfo.mTerminalId);
         final ArrayList<PendingAttribute> bigrams = mBigramReader.readTargetsAndFrequencies(
-                nodeInfo.mTerminalId, mTerminalAddressTableBuffer);
+                nodeInfo.mTerminalId, mTerminalAddressTableBuffer, options);
 
         return new PtNodeInfo(ptNodePos, ptNodePos + nodeInfo.mNodeSize, nodeInfo.mFlags,
                 nodeInfo.mCharacters, frequency, nodeInfo.mParentPos, nodeInfo.mChildrenPos,
diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
index 1dc1f5a..c427656 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
@@ -21,7 +21,11 @@
 import android.util.Pair;
 
 import com.android.inputmethod.latin.makedict.CodePointUtils;
+import com.android.inputmethod.latin.makedict.DictDecoder;
 import com.android.inputmethod.latin.makedict.FormatSpec;
+import com.android.inputmethod.latin.makedict.FusionDictionary;
+import com.android.inputmethod.latin.makedict.FusionDictionary.PtNode;
+import com.android.inputmethod.latin.makedict.UnsupportedFormatException;
 import com.android.inputmethod.latin.utils.FileUtils;
 
 import java.io.File;
@@ -98,6 +102,10 @@
                 getContext().getCacheDir());
         FileUtils.deleteRecursively(file);
         Map<String, String> attributeMap = new HashMap<String, String>();
+        attributeMap.put(FormatSpec.FileHeader.DICTIONARY_ID_ATTRIBUTE, dictId);
+        attributeMap.put(FormatSpec.FileHeader.DICTIONARY_LOCALE_ATTRIBUTE, dictId);
+        attributeMap.put(FormatSpec.FileHeader.DICTIONARY_VERSION_ATTRIBUTE,
+                String.valueOf(TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis())));
         attributeMap.put(FormatSpec.FileHeader.USES_FORGETTING_CURVE_ATTRIBUTE,
                 FormatSpec.FileHeader.ATTRIBUTE_VALUE_TRUE);
         attributeMap.put(FormatSpec.FileHeader.HAS_HISTORICAL_INFO_ATTRIBUTE,
@@ -119,6 +127,50 @@
         return BinaryDictionary.setCurrentTimeForTest(-1);
     }
 
+    public void testReadDictInJavaSide() {
+        testReadDictInJavaSide(FormatSpec.VERSION4);
+    }
+
+    private void testReadDictInJavaSide(final int formatVersion) {
+        setCurrentTimeForTestMode(mCurrentTime);
+        File dictFile = null;
+        try {
+            dictFile = createEmptyDictionaryAndGetFile("TestBinaryDictionary", formatVersion);
+        } catch (IOException e) {
+            fail("IOException while writing an initial dictionary : " + e);
+        }
+        BinaryDictionary binaryDictionary = new BinaryDictionary(dictFile.getAbsolutePath(),
+                0 /* offset */, dictFile.length(), true /* useFullEditDistance */,
+                Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
+        addUnigramWord(binaryDictionary, "a", DUMMY_PROBABILITY);
+        addUnigramWord(binaryDictionary, "ab", DUMMY_PROBABILITY);
+        addUnigramWord(binaryDictionary, "aaa", DUMMY_PROBABILITY);
+        addBigramWords(binaryDictionary, "a", "aaa", DUMMY_PROBABILITY);
+        binaryDictionary.flushWithGC();
+        binaryDictionary.close();
+
+        final DictDecoder dictDecoder = FormatSpec.getDictDecoder(dictFile);
+        try {
+            final FusionDictionary dict = dictDecoder.readDictionaryBinary(null,
+                    false /* deleteDictIfBroken */);
+            PtNode ptNode = FusionDictionary.findWordInTree(dict.mRootNodeArray, "a");
+            assertNotNull(ptNode);
+            assertTrue(ptNode.isTerminal());
+            assertNotNull(ptNode.getBigram("aaa"));
+            ptNode = FusionDictionary.findWordInTree(dict.mRootNodeArray, "ab");
+            assertNotNull(ptNode);
+            assertTrue(ptNode.isTerminal());
+            ptNode = FusionDictionary.findWordInTree(dict.mRootNodeArray, "aaa");
+            assertNotNull(ptNode);
+            assertTrue(ptNode.isTerminal());
+        } catch (IOException e) {
+            fail("IOException while reading dictionary: " + e);
+        } catch (UnsupportedFormatException e) {
+            fail("Unsupported format: " + e);
+        }
+        dictFile.delete();
+    }
+
     public void testControlCurrentTime() {
         testControlCurrentTime(FormatSpec.VERSION4);
     }
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
index b5a71f0..8a1ac52 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
@@ -17,11 +17,11 @@
 package com.android.inputmethod.latin.makedict;
 
 import android.test.AndroidTestCase;
-import android.test.MoreAsserts;
 import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Log;
 import android.util.SparseArray;
 
+import com.android.inputmethod.latin.BinaryDictionary;
 import com.android.inputmethod.latin.makedict.BinaryDictDecoderUtils.CharEncoding;
 import com.android.inputmethod.latin.makedict.BinaryDictDecoderUtils.DictBuffer;
 import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
@@ -76,6 +76,7 @@
 
     public BinaryDictDecoderEncoderTests(final long seed, final int maxUnigrams) {
         super();
+        BinaryDictionary.setCurrentTimeForTest(0);
         Log.e(TAG, "Testing dictionary: seed is " + seed);
         final Random random = new Random(seed);
         sWords.clear();
@@ -262,7 +263,7 @@
                 getContext().getCacheDir());
 
         final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
-                BinaryDictUtils.makeDictionaryOptions(dictName, dictVersion));
+                BinaryDictUtils.makeDictionaryOptions(dictName, dictVersion, formatOptions));
         addUnigrams(words.size(), dict, words, shortcuts);
         addBigrams(dict, words, bigrams);
         checkDictionary(dict, words, bigrams, shortcuts);
@@ -317,7 +318,6 @@
                 BinaryDictUtils.VERSION4_OPTIONS_WITHOUT_TIMESTAMP);
         runReadAndWriteTests(results, BinaryDictUtils.USE_BYTE_BUFFER,
                 BinaryDictUtils.VERSION4_OPTIONS_WITH_TIMESTAMP);
-
         for (final String result : results) {
             Log.d(TAG, result);
         }
@@ -344,14 +344,16 @@
             final SparseArray<List<Integer>> expectedBigrams,
             final TreeMap<Integer, String> resultWords,
             final TreeMap<Integer, Integer> resultFrequencies,
-            final TreeMap<Integer, ArrayList<PendingAttribute>> resultBigrams) {
+            final TreeMap<Integer, ArrayList<PendingAttribute>> resultBigrams,
+            final boolean checkProbability) {
         // check unigrams
         final Set<String> actualWordsSet = new HashSet<String>(resultWords.values());
         final Set<String> expectedWordsSet = new HashSet<String>(expectedWords);
         assertEquals(actualWordsSet, expectedWordsSet);
-
-        for (int freq : resultFrequencies.values()) {
-            assertEquals(freq, UNIGRAM_FREQ);
+        if (checkProbability) {
+            for (int freq : resultFrequencies.values()) {
+                assertEquals(freq, UNIGRAM_FREQ);
+            }
         }
 
         // check bigrams
@@ -377,16 +379,19 @@
                 }
                 actBigrams.get(word1).add(word2);
 
-                final int bigramFreq = BinaryDictIOUtils.reconstructBigramFrequency(
-                        unigramFreq, attr.mFrequency);
-                assertTrue(Math.abs(bigramFreq - BIGRAM_FREQ) < TOLERANCE_OF_BIGRAM_FREQ);
+                if (checkProbability) {
+                    final int bigramFreq = BinaryDictIOUtils.reconstructBigramFrequency(
+                            unigramFreq, attr.mFrequency);
+                    assertTrue(Math.abs(bigramFreq - BIGRAM_FREQ) < TOLERANCE_OF_BIGRAM_FREQ);
+                }
             }
         }
         assertEquals(actBigrams, expBigrams);
     }
 
     private long timeAndCheckReadUnigramsAndBigramsBinary(final File file, final List<String> words,
-            final SparseArray<List<Integer>> bigrams, final int bufferType) {
+            final SparseArray<List<Integer>> bigrams, final int bufferType,
+            final boolean checkProbability) {
         final TreeMap<Integer, String> resultWords = CollectionUtils.newTreeMap();
         final TreeMap<Integer, ArrayList<PendingAttribute>> resultBigrams =
                 CollectionUtils.newTreeMap();
@@ -404,7 +409,7 @@
             Log.e(TAG, "UnsupportedFormatException", e);
         }
 
-        checkWordMap(words, bigrams, resultWords, resultFreqs, resultBigrams);
+        checkWordMap(words, bigrams, resultWords, resultFreqs, resultBigrams, checkProbability);
         return diff;
     }
 
@@ -418,13 +423,17 @@
 
         // making the dictionary from lists of words.
         final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
-                BinaryDictUtils.makeDictionaryOptions(dictName, dictVersion));
+                BinaryDictUtils.makeDictionaryOptions(dictName, dictVersion, formatOptions));
         addUnigrams(words.size(), dict, words, null /* shortcutMap */);
         addBigrams(dict, words, bigrams);
 
         timeWritingDictToFile(file, dict, formatOptions);
 
-        long wordMap = timeAndCheckReadUnigramsAndBigramsBinary(file, words, bigrams, bufferType);
+        // Caveat: Currently, the Java code to read a v4 dictionary doesn't calculate the
+        // probability when there's a timestamp for the entry.
+        // TODO: Abandon the Java code, and implement the v4 dictionary reading code in native.
+        long wordMap = timeAndCheckReadUnigramsAndBigramsBinary(file, words, bigrams, bufferType,
+                !formatOptions.mHasTimestamp /* checkProbability */);
         long fullReading = timeReadingAndCheckDict(file, words, bigrams, null /* shortcutMap */,
                 bufferType);
 
@@ -517,7 +526,7 @@
                 getContext().getCacheDir());
 
         final FusionDictionary dict = new FusionDictionary(new PtNodeArray(),
-                BinaryDictUtils.makeDictionaryOptions(dictName, dictVersion));
+                BinaryDictUtils.makeDictionaryOptions(dictName, dictVersion, formatOptions));
         addUnigrams(sWords.size(), dict, sWords, null /* shortcutMap */);
         addBigrams(dict, words, bigrams);
         timeWritingDictToFile(file, dict, formatOptions);
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictUtils.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictUtils.java
index f7a808c..f175968 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictUtils.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictUtils.java
@@ -36,11 +36,18 @@
     public static final FormatSpec.FormatOptions VERSION4_OPTIONS_WITH_TIMESTAMP =
             new FormatSpec.FormatOptions(FormatSpec.VERSION4, true /* hasTimestamp */);
 
-    public static DictionaryOptions makeDictionaryOptions(final String id, final String version) {
+    public static DictionaryOptions makeDictionaryOptions(final String id, final String version,
+            final FormatSpec.FormatOptions formatOptions) {
         final DictionaryOptions options = new DictionaryOptions(new HashMap<String, String>());
         options.mAttributes.put(FileHeader.DICTIONARY_LOCALE_ATTRIBUTE, "en_US");
         options.mAttributes.put(FileHeader.DICTIONARY_ID_ATTRIBUTE, id);
         options.mAttributes.put(FileHeader.DICTIONARY_VERSION_ATTRIBUTE, version);
+        if (formatOptions.mHasTimestamp) {
+            options.mAttributes.put(FileHeader.HAS_HISTORICAL_INFO_ATTRIBUTE,
+                    FileHeader.ATTRIBUTE_VALUE_TRUE);
+            options.mAttributes.put(FileHeader.USES_FORGETTING_CURVE_ATTRIBUTE,
+                    FileHeader.ATTRIBUTE_VALUE_TRUE);
+        }
         return options;
     }