diff --git a/java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java
index 366f3d4..b70362f 100644
--- a/java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ContactsBinaryDictionary.java
@@ -72,8 +72,8 @@
     private final boolean mUseFirstLastBigrams;
 
     public ContactsBinaryDictionary(final Context context, final Locale locale) {
-        super(context, getFilenameWithLocale(NAME, locale.toString()), Dictionary.TYPE_CONTACTS,
-                false /* isUpdatable */);
+        super(context, getFilenameWithLocale(NAME, locale), locale,
+                Dictionary.TYPE_CONTACTS, false /* isUpdatable */);
         mLocale = locale;
         mUseFirstLastBigrams = useFirstLastBigramsForLocale(locale);
         registerObserver(context);
diff --git a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
index 17cb715..154e9b5 100644
--- a/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/ExpandableBinaryDictionary.java
@@ -33,8 +33,10 @@
 import java.io.File;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
@@ -99,6 +101,9 @@
      */
     private final String mFilename;
 
+    /** Dictionary locale */
+    private final Locale mLocale;
+
     /** Whether to support dynamically updating the dictionary */
     private final boolean mIsUpdatable;
 
@@ -183,15 +188,17 @@
      * @param context The application context of the parent.
      * @param filename The filename for this binary dictionary. Multiple dictionaries with the same
      *        filename is supported.
+     * @param locale the dictionary locale.
      * @param dictType the dictionary type, as a human-readable string
      * @param isUpdatable whether to support dynamically updating the dictionary. Please note that
      *        dynamic dictionary has negative effects on memory space and computation time.
      */
     public ExpandableBinaryDictionary(final Context context, final String filename,
-            final String dictType, final boolean isUpdatable) {
+            final Locale locale, final String dictType, final boolean isUpdatable) {
         super(dictType);
         mFilename = filename;
         mContext = context;
+        mLocale = locale;
         mIsUpdatable = isUpdatable;
         mBinaryDictionary = null;
         mFilenameDictionaryUpdateController = getDictionaryUpdateController(filename);
@@ -199,8 +206,8 @@
         mDictionaryWriter = getDictionaryWriter(context, dictType, isUpdatable);
     }
 
-    protected static String getFilenameWithLocale(final String name, final String localeStr) {
-        return name + "." + localeStr + DICT_FILE_EXTENSION;
+    protected static String getFilenameWithLocale(final String name, final Locale locale) {
+        return name + "." + locale.toString() + DICT_FILE_EXTENSION;
     }
 
     /**
@@ -237,9 +244,10 @@
 
     protected Map<String, String> getHeaderAttributeMap() {
         HashMap<String, String> attributeMap = new HashMap<String, String>();
-        attributeMap.put(FormatSpec.FileHeader.SUPPORTS_DYNAMIC_UPDATE_ATTRIBUTE,
-                SUPPORTS_DYNAMIC_UPDATE);
         attributeMap.put(FormatSpec.FileHeader.DICTIONARY_ID_ATTRIBUTE, mFilename);
+        attributeMap.put(FormatSpec.FileHeader.DICTIONARY_LOCALE_ATTRIBUTE, mLocale.toString());
+        attributeMap.put(FormatSpec.FileHeader.DICTIONARY_VERSION_ATTRIBUTE,
+                String.valueOf(TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis())));
         return attributeMap;
     }
 
diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index 6f9dd67..8ce1e38 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -614,7 +614,6 @@
         final Locale switcherSubtypeLocale = mSubtypeSwitcher.getCurrentSubtypeLocale();
         final String switcherLocaleStr = switcherSubtypeLocale.toString();
         final Locale subtypeLocale;
-        final String localeStr;
         if (TextUtils.isEmpty(switcherLocaleStr)) {
             // This happens in very rare corner cases - for example, immediately after a switch
             // to LatinIME has been requested, about a frame later another switch happens. In this
@@ -624,10 +623,8 @@
             // of knowing anyway.
             Log.e(TAG, "System is reporting no current subtype.");
             subtypeLocale = getResources().getConfiguration().locale;
-            localeStr = subtypeLocale.toString();
         } else {
             subtypeLocale = switcherSubtypeLocale;
-            localeStr = switcherLocaleStr;
         }
 
         final Suggest newSuggest = new Suggest(this /* Context */, subtypeLocale,
@@ -642,19 +639,20 @@
             ResearchLogger.getInstance().initSuggest(newSuggest);
         }
 
-        mUserDictionary = new UserBinaryDictionary(this, localeStr);
+        mUserDictionary = new UserBinaryDictionary(this, subtypeLocale);
         mIsUserDictionaryAvailable = mUserDictionary.isEnabled();
         newSuggest.setUserDictionary(mUserDictionary);
 
         final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
 
-        mUserHistoryDictionary = PersonalizationHelper.getUserHistoryDictionary(this, localeStr);
+        mUserHistoryDictionary = PersonalizationHelper.getUserHistoryDictionary(
+                this, subtypeLocale);
         newSuggest.setUserHistoryDictionary(mUserHistoryDictionary);
         mPersonalizationDictionary =
-                PersonalizationHelper.getPersonalizationDictionary(this, localeStr);
+                PersonalizationHelper.getPersonalizationDictionary(this, subtypeLocale);
         newSuggest.setPersonalizationDictionary(mPersonalizationDictionary);
         mPersonalizationPredictionDictionary =
-                PersonalizationHelper.getPersonalizationPredictionDictionary(this, localeStr);
+                PersonalizationHelper.getPersonalizationPredictionDictionary(this, subtypeLocale);
         newSuggest.setPersonalizationPredictionDictionary(mPersonalizationPredictionDictionary);
 
         final Suggest oldSuggest = mSuggest;
diff --git a/java/src/com/android/inputmethod/latin/SynchronouslyLoadedUserBinaryDictionary.java b/java/src/com/android/inputmethod/latin/SynchronouslyLoadedUserBinaryDictionary.java
index 6405b5e..9cb2f5b 100644
--- a/java/src/com/android/inputmethod/latin/SynchronouslyLoadedUserBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/SynchronouslyLoadedUserBinaryDictionary.java
@@ -22,14 +22,15 @@
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
 
 import java.util.ArrayList;
+import java.util.Locale;
 
 public final class SynchronouslyLoadedUserBinaryDictionary extends UserBinaryDictionary {
 
-    public SynchronouslyLoadedUserBinaryDictionary(final Context context, final String locale) {
+    public SynchronouslyLoadedUserBinaryDictionary(final Context context, final Locale locale) {
         this(context, locale, false);
     }
 
-    public SynchronouslyLoadedUserBinaryDictionary(final Context context, final String locale,
+    public SynchronouslyLoadedUserBinaryDictionary(final Context context, final Locale locale,
             final boolean alsoUseMoreRestrictiveLocales) {
         super(context, locale, alsoUseMoreRestrictiveLocales);
     }
diff --git a/java/src/com/android/inputmethod/latin/UserBinaryDictionary.java b/java/src/com/android/inputmethod/latin/UserBinaryDictionary.java
index 15b3d8d..cc7687b 100644
--- a/java/src/com/android/inputmethod/latin/UserBinaryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/UserBinaryDictionary.java
@@ -75,20 +75,21 @@
     final private String mLocale;
     final private boolean mAlsoUseMoreRestrictiveLocales;
 
-    public UserBinaryDictionary(final Context context, final String locale) {
+    public UserBinaryDictionary(final Context context, final Locale locale) {
         this(context, locale, false);
     }
 
-    public UserBinaryDictionary(final Context context, final String locale,
+    public UserBinaryDictionary(final Context context, final Locale locale,
             final boolean alsoUseMoreRestrictiveLocales) {
-        super(context, getFilenameWithLocale(NAME, locale), Dictionary.TYPE_USER,
+        super(context, getFilenameWithLocale(NAME, locale), locale, Dictionary.TYPE_USER,
                 false /* isUpdatable */);
         if (null == locale) throw new NullPointerException(); // Catch the error earlier
-        if (SubtypeLocaleUtils.NO_LANGUAGE.equals(locale)) {
+        final String localeStr = locale.toString();
+        if (SubtypeLocaleUtils.NO_LANGUAGE.equals(localeStr)) {
             // If we don't have a locale, insert into the "all locales" user dictionary.
             mLocale = USER_DICTIONARY_ALL_LANGUAGES;
         } else {
-            mLocale = locale;
+            mLocale = localeStr;
         }
         mAlsoUseMoreRestrictiveLocales = alsoUseMoreRestrictiveLocales;
         // Perform a managed query. The Activity will handle closing and re-querying the cursor
diff --git a/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java b/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
index dbf6d00..8f26f84 100644
--- a/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
+++ b/java/src/com/android/inputmethod/latin/personalization/DecayingExpandableBinaryDictionaryBase.java
@@ -35,7 +35,9 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
 
 /**
  * This class is a base class of a dictionary that supports decaying for the personalized language
@@ -55,7 +57,7 @@
     public static final int REQUIRED_BINARY_DICTIONARY_VERSION = 4;
 
     /** Locale for which this user history dictionary is storing words */
-    private final String mLocale;
+    private final Locale mLocale;
 
     private final String mFileName;
 
@@ -66,11 +68,11 @@
     @UsedForTesting boolean mIsTest = false;
 
     /* package */ DecayingExpandableBinaryDictionaryBase(final Context context,
-            final String locale, final String dictionaryType, final String fileName) {
-        super(context, fileName, dictionaryType, true);
+            final Locale locale, final String dictionaryType, final String fileName) {
+        super(context, fileName, locale, dictionaryType, true);
         mLocale = locale;
         mFileName = fileName;
-        if (mLocale != null && mLocale.length() > 1) {
+        if (mLocale != null && mLocale.toString().length() > 1) {
             reloadDictionaryIfRequired();
         }
     }
@@ -93,7 +95,9 @@
         attributeMap.put(FormatSpec.FileHeader.USES_FORGETTING_CURVE_ATTRIBUTE,
                 FormatSpec.FileHeader.ATTRIBUTE_VALUE_TRUE);
         attributeMap.put(FormatSpec.FileHeader.DICTIONARY_ID_ATTRIBUTE, mFileName);
-        attributeMap.put(FormatSpec.FileHeader.DICTIONARY_LOCALE_ATTRIBUTE, mLocale);
+        attributeMap.put(FormatSpec.FileHeader.DICTIONARY_LOCALE_ATTRIBUTE, mLocale.toString());
+        attributeMap.put(FormatSpec.FileHeader.DICTIONARY_VERSION_ATTRIBUTE,
+                String.valueOf(TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis())));
         return attributeMap;
     }
 
@@ -164,10 +168,6 @@
         // Never loaded to memory in Java side.
     }
 
-    protected String getLocale() {
-        return mLocale;
-    }
-
     public void registerUpdateSession(PersonalizationDictionaryUpdateSession session) {
         session.setPredictionDictionary(this);
         mSessions.add(session);
diff --git a/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionary.java b/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionary.java
index 67015f4..8d3dcc3 100644
--- a/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionary.java
+++ b/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionary.java
@@ -21,9 +21,9 @@
 import com.android.inputmethod.latin.utils.CollectionUtils;
 
 import android.content.Context;
-import android.content.SharedPreferences;
 
 import java.util.ArrayList;
+import java.util.Locale;
 
 /**
  * This class is a dictionary for the personalized language model that uses binary dictionary.
@@ -33,14 +33,10 @@
     private final ArrayList<PersonalizationDictionaryUpdateSession> mSessions =
             CollectionUtils.newArrayList();
 
-    /** Locale for which this user history dictionary is storing words */
-    private final String mLocale;
-
-    public PersonalizationDictionary(final Context context, final String locale) {
+    public PersonalizationDictionary(final Context context, final Locale locale) {
         // TODO: Make isUpdatable true.
-        super(context, getFilenameWithLocale(NAME, locale), Dictionary.TYPE_PERSONALIZATION,
-                false /* isUpdatable */);
-        mLocale = locale;
+        super(context, getFilenameWithLocale(NAME, locale), locale,
+                Dictionary.TYPE_PERSONALIZATION, false /* isUpdatable */);
         // TODO: Restore last updated time
         loadDictionary();
     }
diff --git a/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java b/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
index a47cc4d..f73bb28 100644
--- a/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
+++ b/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
@@ -24,6 +24,7 @@
 import android.util.Log;
 
 import java.lang.ref.SoftReference;
+import java.util.Locale;
 import java.util.concurrent.ConcurrentHashMap;
 
 public class PersonalizationHelper {
@@ -41,11 +42,12 @@
                             CollectionUtils.newConcurrentHashMap();
 
     public static UserHistoryDictionary getUserHistoryDictionary(
-            final Context context, final String locale) {
+            final Context context, final Locale locale) {
+        final String localeStr = locale.toString();
         synchronized (sLangUserHistoryDictCache) {
-            if (sLangUserHistoryDictCache.containsKey(locale)) {
+            if (sLangUserHistoryDictCache.containsKey(localeStr)) {
                 final SoftReference<UserHistoryDictionary> ref =
-                        sLangUserHistoryDictCache.get(locale);
+                        sLangUserHistoryDictCache.get(localeStr);
                 final UserHistoryDictionary dict = ref == null ? null : ref.get();
                 if (dict != null) {
                     if (DEBUG) {
@@ -56,7 +58,8 @@
                 }
             }
             final UserHistoryDictionary dict = new UserHistoryDictionary(context, locale);
-            sLangUserHistoryDictCache.put(locale, new SoftReference<UserHistoryDictionary>(dict));
+            sLangUserHistoryDictCache.put(localeStr,
+                    new SoftReference<UserHistoryDictionary>(dict));
             return dict;
         }
     }
@@ -74,7 +77,7 @@
     }
 
     public static void registerPersonalizationDictionaryUpdateSession(final Context context,
-            final PersonalizationDictionaryUpdateSession session, String locale) {
+            final PersonalizationDictionaryUpdateSession session, Locale locale) {
         final PersonalizationPredictionDictionary predictionDictionary =
                 getPersonalizationPredictionDictionary(context, locale);
         predictionDictionary.registerUpdateSession(session);
@@ -83,11 +86,12 @@
     }
 
     public static PersonalizationDictionary getPersonalizationDictionary(
-            final Context context, final String locale) {
+            final Context context, final Locale locale) {
+        final String localeStr = locale.toString();
         synchronized (sLangPersonalizationDictCache) {
-            if (sLangPersonalizationDictCache.containsKey(locale)) {
+            if (sLangPersonalizationDictCache.containsKey(localeStr)) {
                 final SoftReference<PersonalizationDictionary> ref =
-                        sLangPersonalizationDictCache.get(locale);
+                        sLangPersonalizationDictCache.get(localeStr);
                 final PersonalizationDictionary dict = ref == null ? null : ref.get();
                 if (dict != null) {
                     if (DEBUG) {
@@ -98,17 +102,18 @@
             }
             final PersonalizationDictionary dict = new PersonalizationDictionary(context, locale);
             sLangPersonalizationDictCache.put(
-                    locale, new SoftReference<PersonalizationDictionary>(dict));
+                    localeStr, new SoftReference<PersonalizationDictionary>(dict));
             return dict;
         }
     }
 
     public static PersonalizationPredictionDictionary getPersonalizationPredictionDictionary(
-            final Context context, final String locale) {
+            final Context context, final Locale locale) {
+        final String localeStr = locale.toString();
         synchronized (sLangPersonalizationPredictionDictCache) {
-            if (sLangPersonalizationPredictionDictCache.containsKey(locale)) {
+            if (sLangPersonalizationPredictionDictCache.containsKey(localeStr)) {
                 final SoftReference<PersonalizationPredictionDictionary> ref =
-                        sLangPersonalizationPredictionDictCache.get(locale);
+                        sLangPersonalizationPredictionDictCache.get(localeStr);
                 final PersonalizationPredictionDictionary dict = ref == null ? null : ref.get();
                 if (dict != null) {
                     if (DEBUG) {
@@ -120,7 +125,7 @@
             final PersonalizationPredictionDictionary dict =
                     new PersonalizationPredictionDictionary(context, locale);
             sLangPersonalizationPredictionDictCache.put(
-                    locale, new SoftReference<PersonalizationPredictionDictionary>(dict));
+                    localeStr, new SoftReference<PersonalizationPredictionDictionary>(dict));
             return dict;
         }
     }
diff --git a/java/src/com/android/inputmethod/latin/personalization/PersonalizationPredictionDictionary.java b/java/src/com/android/inputmethod/latin/personalization/PersonalizationPredictionDictionary.java
index 16107e2..6d94716 100644
--- a/java/src/com/android/inputmethod/latin/personalization/PersonalizationPredictionDictionary.java
+++ b/java/src/com/android/inputmethod/latin/personalization/PersonalizationPredictionDictionary.java
@@ -19,14 +19,16 @@
 import com.android.inputmethod.latin.Dictionary;
 import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 
+import java.util.Locale;
+
 import android.content.Context;
 
 public class PersonalizationPredictionDictionary extends DecayingExpandableBinaryDictionaryBase {
     private static final String NAME = PersonalizationPredictionDictionary.class.getSimpleName();
 
-    /* package */ PersonalizationPredictionDictionary(final Context context, final String locale) {
+    /* package */ PersonalizationPredictionDictionary(final Context context, final Locale locale) {
         super(context, locale, Dictionary.TYPE_PERSONALIZATION_PREDICTION_IN_JAVA,
-                getDictionaryFileName(locale));
+                getDictionaryFileName(locale.toString()));
     }
 
     private static String getDictionaryFileName(final String locale) {
diff --git a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
index 95a6fe1..60370d8 100644
--- a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
@@ -19,6 +19,8 @@
 import com.android.inputmethod.latin.Dictionary;
 import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 
+import java.util.Locale;
+
 import android.content.Context;
 
 /**
@@ -28,8 +30,9 @@
 public class UserHistoryDictionary extends DecayingExpandableBinaryDictionaryBase {
     /* package for tests */ static final String NAME =
             UserHistoryDictionary.class.getSimpleName();
-    /* package */ UserHistoryDictionary(final Context context, final String locale) {
-        super(context, locale, Dictionary.TYPE_USER_HISTORY, getDictionaryFileName(locale));
+    /* package */ UserHistoryDictionary(final Context context, final Locale locale) {
+        super(context, locale, Dictionary.TYPE_USER_HISTORY,
+                getDictionaryFileName(locale.toString()));
     }
 
     private static String getDictionaryFileName(final String locale) {
diff --git a/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerService.java b/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerService.java
index 503b18b..c108b20 100644
--- a/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerService.java
+++ b/java/src/com/android/inputmethod/latin/spellcheck/AndroidSpellCheckerService.java
@@ -428,7 +428,7 @@
         final String localeStr = locale.toString();
         UserBinaryDictionary userDictionary = mUserDictionaries.get(localeStr);
         if (null == userDictionary) {
-            userDictionary = new SynchronouslyLoadedUserBinaryDictionary(this, localeStr, true);
+            userDictionary = new SynchronouslyLoadedUserBinaryDictionary(this, locale, true);
             mUserDictionaries.put(localeStr, userDictionary);
         }
         dictionaryCollection.addDictionary(userDictionary);
diff --git a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
index 9c93b8b..beac57b 100644
--- a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
@@ -26,6 +26,7 @@
 import java.io.File;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 import java.util.Random;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
@@ -84,7 +85,7 @@
         final List<String> words = generateWords(numberOfWords, random);
         final UserHistoryDictionary dict =
                 PersonalizationHelper.getUserHistoryDictionary(getContext(),
-                        testFilenameSuffix /* locale */);
+                        new Locale(testFilenameSuffix));
         // Add random words to the user history dictionary.
         addToDict(dict, words);
         if (checkContents) {
@@ -108,7 +109,7 @@
     private void clearHistory(final String testFilenameSuffix) {
         final UserHistoryDictionary dict =
                 PersonalizationHelper.getUserHistoryDictionary(getContext(),
-                        testFilenameSuffix /* locale */);
+                        new Locale(testFilenameSuffix));
         dict.clearAndFlushDictionary();
         dict.close();
     }
@@ -121,7 +122,7 @@
         try {
             final UserHistoryDictionary dict =
                     PersonalizationHelper.getUserHistoryDictionary(getContext(),
-                            testFilenameSuffix);
+                            new Locale(testFilenameSuffix));
             dict.shutdownExecutorForTests();
             while (!dict.isTerminatedForTests()) {
                 Thread.sleep(WAIT_TERMINATING_IN_MILLISECONDS);
@@ -134,7 +135,7 @@
     public void testRandomWords() {
         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 = "testRandomWords" + System.currentTimeMillis();
+        final String testFilenameSuffix = "test_random_words" + System.currentTimeMillis();
         final String fileName = UserHistoryDictionary.NAME + "." + testFilenameSuffix
                 + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
 
@@ -169,7 +170,7 @@
 
             // Create filename suffixes for this test.
             for (int i = 0; i < numberOfLanguages; i++) {
-                testFilenameSuffixes[i] = "testSwitchingLanguages" + i;
+                testFilenameSuffixes[i] = "test_switching_languages" + i;
                 final String fileName = UserHistoryDictionary.NAME + "." +
                         testFilenameSuffixes[i] + ExpandableBinaryDictionary.DICT_FILE_EXTENSION;
                 dictFiles[i] = new File(getContext().getFilesDir(), fileName);
@@ -205,7 +206,7 @@
     }
 
     public void testAddManyWords() {
-        final String testFilenameSuffix = "testRandomWords" + System.currentTimeMillis();
+        final String testFilenameSuffix = "test_random_words" + System.currentTimeMillis();
         final int numberOfWords = 10000;
         final Random random = new Random(123456);
         clearHistory(testFilenameSuffix);