diff --git a/java/src/com/android/inputmethod/latin/DictionaryFactory.java b/java/src/com/android/inputmethod/latin/DictionaryFactory.java
index 828e54f..3721132 100644
--- a/java/src/com/android/inputmethod/latin/DictionaryFactory.java
+++ b/java/src/com/android/inputmethod/latin/DictionaryFactory.java
@@ -51,7 +51,7 @@
         if (null == locale) {
             Log.e(TAG, "No locale defined for dictionary");
             return new DictionaryCollection(Dictionary.TYPE_MAIN,
-                    createReadOnlyBinaryDictionary(context, locale));
+                    createBinaryDictionary(context, locale));
         }
 
         final LinkedList<Dictionary> dictList = CollectionUtils.newLinkedList();
@@ -59,11 +59,11 @@
                 BinaryDictionaryGetter.getDictionaryFiles(locale, context);
         if (null != assetFileList) {
             for (final AssetFileAddress f : assetFileList) {
-                final ReadOnlyBinaryDictionary readOnlyBinaryDictionary =
-                        new ReadOnlyBinaryDictionary(f.mFilename, f.mOffset, f.mLength,
-                                useFullEditDistance, locale, Dictionary.TYPE_MAIN);
-                if (readOnlyBinaryDictionary.isValidDictionary()) {
-                    dictList.add(readOnlyBinaryDictionary);
+                final BinaryDictionary binaryDictionary = new BinaryDictionary(f.mFilename,
+                        f.mOffset, f.mLength, useFullEditDistance, locale, Dictionary.TYPE_MAIN,
+                        false /* isUpdatable */);
+                if (binaryDictionary.isValidDictionary()) {
+                    dictList.add(binaryDictionary);
                 }
             }
         }
@@ -89,12 +89,12 @@
     }
 
     /**
-     * Initializes a read-only binary dictionary from a raw resource file
+     * Initializes a dictionary from a raw resource file
      * @param context application context for reading resources
      * @param locale the locale to use for the resource
-     * @return an initialized instance of ReadOnlyBinaryDictionary
+     * @return an initialized instance of BinaryDictionary
      */
-    protected static ReadOnlyBinaryDictionary createReadOnlyBinaryDictionary(final Context context,
+    protected static BinaryDictionary createBinaryDictionary(final Context context,
             final Locale locale) {
         AssetFileDescriptor afd = null;
         try {
@@ -113,8 +113,9 @@
                 Log.e(TAG, "sourceDir is not a file: " + sourceDir);
                 return null;
             }
-            return new ReadOnlyBinaryDictionary(sourceDir, afd.getStartOffset(), afd.getLength(),
-                    false /* useFullEditDistance */, locale, Dictionary.TYPE_MAIN);
+            return new BinaryDictionary(sourceDir, afd.getStartOffset(), afd.getLength(),
+                    false /* useFullEditDistance */, locale, Dictionary.TYPE_MAIN,
+                    false /* isUpdatable */);
         } catch (android.content.res.Resources.NotFoundException e) {
             Log.e(TAG, "Could not find the resource");
             return null;
@@ -141,10 +142,10 @@
         final DictionaryCollection dictionaryCollection =
                 new DictionaryCollection(Dictionary.TYPE_MAIN);
         for (final AssetFileAddress address : dictionaryList) {
-            final ReadOnlyBinaryDictionary readOnlyBinaryDictionary = new ReadOnlyBinaryDictionary(
-                    address.mFilename, address.mOffset, address.mLength, useFullEditDistance,
-                    locale, Dictionary.TYPE_MAIN);
-            dictionaryCollection.addDictionary(readOnlyBinaryDictionary);
+            final BinaryDictionary binaryDictionary = new BinaryDictionary(address.mFilename,
+                    address.mOffset, address.mLength, useFullEditDistance, locale,
+                    Dictionary.TYPE_MAIN, false /* isUpdatable */);
+            dictionaryCollection.addDictionary(binaryDictionary);
         }
         return dictionaryCollection;
     }
diff --git a/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java
deleted file mode 100644
index 68505ce..0000000
--- a/java/src/com/android/inputmethod/latin/ReadOnlyBinaryDictionary.java
+++ /dev/null
@@ -1,120 +0,0 @@
-/*
- * Copyright (C) 2013 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.inputmethod.latin;
-
-import com.android.inputmethod.keyboard.ProximityInfo;
-import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
-
-import java.util.ArrayList;
-import java.util.Locale;
-import java.util.concurrent.locks.ReentrantReadWriteLock;
-
-/**
- * This class provides binary dictionary reading operations with locking. An instance of this class
- * can be used by multiple threads. Note that different session IDs must be used when multiple
- * threads get suggestions using this class.
- */
-public final class ReadOnlyBinaryDictionary extends Dictionary {
-    /**
-     * A lock for accessing binary dictionary. Only closing binary dictionary is the operation
-     * that change the state of dictionary.
-     */
-    private final ReentrantReadWriteLock mLock = new ReentrantReadWriteLock();
-
-    private final BinaryDictionary mBinaryDictionary;
-
-    public ReadOnlyBinaryDictionary(final String filename, final long offset, final long length,
-            final boolean useFullEditDistance, final Locale locale, final String dictType) {
-        super(dictType);
-        mBinaryDictionary = new BinaryDictionary(filename, offset, length, useFullEditDistance,
-                locale, dictType, false /* isUpdatable */);
-    }
-
-    public boolean isValidDictionary() {
-        return mBinaryDictionary.isValidDictionary();
-    }
-
-    @Override
-    public ArrayList<SuggestedWordInfo> getSuggestions(final WordComposer composer,
-            final String prevWord, final ProximityInfo proximityInfo,
-            final boolean blockOffensiveWords, final int[] additionalFeaturesOptions) {
-        return getSuggestionsWithSessionId(composer, prevWord, proximityInfo, blockOffensiveWords,
-                additionalFeaturesOptions, 0 /* sessionId */);
-    }
-
-    @Override
-    public ArrayList<SuggestedWordInfo> getSuggestionsWithSessionId(final WordComposer composer,
-            final String prevWord, final ProximityInfo proximityInfo,
-            final boolean blockOffensiveWords, final int[] additionalFeaturesOptions,
-            final int sessionId) {
-        if (mLock.readLock().tryLock()) {
-            try {
-                return mBinaryDictionary.getSuggestions(composer, prevWord, proximityInfo,
-                        blockOffensiveWords, additionalFeaturesOptions);
-            } finally {
-                mLock.readLock().unlock();
-            }
-        }
-        return null;
-    }
-
-    @Override
-    public boolean isValidWord(final String word) {
-        if (mLock.readLock().tryLock()) {
-            try {
-                return mBinaryDictionary.isValidWord(word);
-            } finally {
-                mLock.readLock().unlock();
-            }
-        }
-        return false;
-    }
-
-    @Override
-    public boolean shouldAutoCommit(final SuggestedWordInfo candidate) {
-        if (mLock.readLock().tryLock()) {
-            try {
-                return mBinaryDictionary.shouldAutoCommit(candidate);
-            } finally {
-                mLock.readLock().unlock();
-            }
-        }
-        return false;
-    }
-
-    @Override
-    public int getFrequency(final String word) {
-        if (mLock.readLock().tryLock()) {
-            try {
-                return mBinaryDictionary.getFrequency(word);
-            } finally {
-                mLock.readLock().unlock();
-            }
-        }
-        return NOT_A_PROBABILITY;
-    }
-
-    @Override
-    public void close() {
-        mLock.writeLock().lock();
-        try {
-            mBinaryDictionary.close();
-        } finally {
-            mLock.writeLock().unlock();
-        }
-    }
-}
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
index 2fa3111..456352c 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.cpp
@@ -26,8 +26,7 @@
 void DynamicPatriciaTrieNodeReader::fetchPtNodeInfoFromBufferAndProcessMovedPtNode(
         const int ptNodePos, const int maxCodePointCount, int *const outCodePoints) {
     if (ptNodePos < 0 || ptNodePos >= mBuffer->getTailPosition()) {
-        // Reading invalid position because of bug or broken dictionary.
-        AKLOGE("Fetching PtNode info from invalid dictionary position: %d, dictionary size: %d",
+        AKLOGE("Fetching PtNode info form invalid dictionary position: %d, dictionary size: %d",
                 ptNodePos, mBuffer->getTailPosition());
         ASSERT(false);
         invalidatePtNodeInfo();
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp
index 601ee66..f4a2ef3 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.cpp
@@ -155,15 +155,6 @@
 // Read node array size and process empty node arrays. Nodes and arrays are counted up in this
 // method to avoid an infinite loop.
 void DynamicPatriciaTrieReadingHelper::nextPtNodeArray() {
-    if (mReadingState.mPos < 0 || mReadingState.mPos >= mBuffer->getTailPosition()) {
-        // Reading invalid position because of a bug or a broken dictionary.
-        AKLOGE("Reading PtNode array info from invalid dictionary position: %d, dict size: %d",
-                mReadingState.mPos, mBuffer->getTailPosition());
-        ASSERT(false);
-        mIsError = true;
-        mReadingState.mPos = NOT_A_DICT_POS;
-        return;
-    }
     mReadingState.mPosOfLastPtNodeArrayHead = mReadingState.mPos;
     const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(mReadingState.mPos);
     const uint8_t *const dictBuf = mBuffer->getBuffer(usesAdditionalBuffer);
@@ -200,15 +191,6 @@
 
 // Follow the forward link and read the next node array if exists.
 void DynamicPatriciaTrieReadingHelper::followForwardLink() {
-    if (mReadingState.mPos < 0 || mReadingState.mPos >= mBuffer->getTailPosition()) {
-        // Reading invalid position because of bug or broken dictionary.
-        AKLOGE("Reading forward link from invalid dictionary position: %d, dict size: %d",
-                mReadingState.mPos, mBuffer->getTailPosition());
-        ASSERT(false);
-        mIsError = true;
-        mReadingState.mPos = NOT_A_DICT_POS;
-        return;
-    }
     const bool usesAdditionalBuffer = mBuffer->isInAdditionalBuffer(mReadingState.mPos);
     const uint8_t *const dictBuf = mBuffer->getBuffer(usesAdditionalBuffer);
     if (usesAdditionalBuffer) {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
index 154590f..b033eee 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h
@@ -240,7 +240,6 @@
     static const int MAX_NODE_ARRAY_COUNT_TO_AVOID_INFINITE_LOOP;
     static const size_t MAX_READING_STATE_STACK_SIZE;
 
-    // TODO: Introduce error code to track what caused the error.
     bool mIsError;
     ReadingState mReadingState;
     const BufferWithExtendableBuffer *const mBuffer;