diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index cb70896..fe27ebf 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -75,6 +75,7 @@
 import com.android.inputmethod.keyboard.MainKeyboardView;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
 import com.android.inputmethod.latin.define.ProductionFlag;
+import com.android.inputmethod.latin.personalization.PersonalizationDictionaryHelper;
 import com.android.inputmethod.latin.personalization.UserHistoryDictionary;
 import com.android.inputmethod.latin.settings.Settings;
 import com.android.inputmethod.latin.settings.SettingsActivity;
@@ -563,7 +564,8 @@
         resetContactsDictionary(oldContactsDictionary);
 
         final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
-        mUserHistoryDictionary = UserHistoryDictionary.getInstance(this, localeStr, prefs);
+        mUserHistoryDictionary =
+                PersonalizationDictionaryHelper.getUserHistoryDictionary(this, localeStr, prefs);
         mSuggest.setUserHistoryDictionary(mUserHistoryDictionary);
     }
 
diff --git a/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryHelper.java b/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryHelper.java
new file mode 100644
index 0000000..e09e834
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/personalization/PersonalizationDictionaryHelper.java
@@ -0,0 +1,53 @@
+/*
+ * 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.personalization;
+
+import com.android.inputmethod.latin.utils.CollectionUtils;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.util.Log;
+
+import java.lang.ref.SoftReference;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class PersonalizationDictionaryHelper {
+    private static final String TAG = PersonalizationDictionaryHelper.class.getSimpleName();
+    private static final boolean DEBUG = false;
+
+    private static final ConcurrentHashMap<String, SoftReference<UserHistoryDictionary>>
+            sLangDictCache = CollectionUtils.newConcurrentHashMap();
+
+    public static UserHistoryDictionary getUserHistoryDictionary(
+            final Context context, final String locale, final SharedPreferences sp) {
+        synchronized (sLangDictCache) {
+            if (sLangDictCache.containsKey(locale)) {
+                final SoftReference<UserHistoryDictionary> ref = sLangDictCache.get(locale);
+                final UserHistoryDictionary dict = ref == null ? null : ref.get();
+                if (dict != null) {
+                    if (DEBUG) {
+                        Log.w(TAG, "Use cached UserHistoryDictionary for " + locale);
+                    }
+                    return dict;
+                }
+            }
+            final UserHistoryDictionary dict = new UserHistoryDictionary(context, locale, sp);
+            sLangDictCache.put(locale, new SoftReference<UserHistoryDictionary>(dict));
+            return dict;
+        }
+    }
+}
diff --git a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
index a8f1a9e..c76dea0 100644
--- a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
@@ -27,12 +27,11 @@
 import com.android.inputmethod.latin.Dictionary;
 import com.android.inputmethod.latin.ExpandableDictionary;
 import com.android.inputmethod.latin.LatinImeLogger;
-import com.android.inputmethod.latin.WordComposer;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
+import com.android.inputmethod.latin.WordComposer;
 import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
 import com.android.inputmethod.latin.settings.Settings;
 import com.android.inputmethod.latin.utils.ByteArrayWrapper;
-import com.android.inputmethod.latin.utils.CollectionUtils;
 import com.android.inputmethod.latin.utils.UserHistoryDictIOUtils;
 import com.android.inputmethod.latin.utils.UserHistoryDictIOUtils.BigramDictionaryInterface;
 import com.android.inputmethod.latin.utils.UserHistoryDictIOUtils.OnAddWordListener;
@@ -44,9 +43,7 @@
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.lang.ref.SoftReference;
 import java.util.ArrayList;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.locks.ReentrantLock;
 
 /**
@@ -88,28 +85,7 @@
     // Should always be false except when we use this class for test
     @UsedForTesting boolean isTest = false;
 
-    private static final ConcurrentHashMap<String, SoftReference<UserHistoryDictionary>>
-            sLangDictCache = CollectionUtils.newConcurrentHashMap();
-
-    public static synchronized UserHistoryDictionary getInstance(
-            final Context context, final String locale, final SharedPreferences sp) {
-        if (sLangDictCache.containsKey(locale)) {
-            final SoftReference<UserHistoryDictionary> ref = sLangDictCache.get(locale);
-            final UserHistoryDictionary dict = ref == null ? null : ref.get();
-            if (dict != null) {
-                if (PROFILE_SAVE_RESTORE) {
-                    Log.w(TAG, "Use cached UserHistoryDictionary for " + locale);
-                }
-                return dict;
-            }
-        }
-        final UserHistoryDictionary dict =
-                new UserHistoryDictionary(context, locale, sp);
-        sLangDictCache.put(locale, new SoftReference<UserHistoryDictionary>(dict));
-        return dict;
-    }
-
-    private UserHistoryDictionary(final Context context, final String locale,
+    /* package */ UserHistoryDictionary(final Context context, final String locale,
             final SharedPreferences sp) {
         super(context, Dictionary.TYPE_USER_HISTORY);
         mLocale = locale;
diff --git a/native/jni/src/suggest/core/dicnode/dic_node.h b/native/jni/src/suggest/core/dicnode/dic_node.h
index cbed204..5c56fe8 100644
--- a/native/jni/src/suggest/core/dicnode/dic_node.h
+++ b/native/jni/src/suggest/core/dicnode/dic_node.h
@@ -18,10 +18,10 @@
 #define LATINIME_DIC_NODE_H
 
 #include "defines.h"
-#include "suggest/core/dicnode/dic_node_state.h"
 #include "suggest/core/dicnode/dic_node_profiler.h"
-#include "suggest/core/dicnode/dic_node_properties.h"
 #include "suggest/core/dicnode/dic_node_release_listener.h"
+#include "suggest/core/dicnode/internal/dic_node_state.h"
+#include "suggest/core/dicnode/internal/dic_node_properties.h"
 #include "suggest/core/dictionary/digraph_utils.h"
 #include "utils/char_utils.h"
 
diff --git a/native/jni/src/suggest/core/dicnode/dic_node_release_listener.h b/native/jni/src/suggest/core/dicnode/dic_node_release_listener.h
index 2a81c3c..2ca4f21 100644
--- a/native/jni/src/suggest/core/dicnode/dic_node_release_listener.h
+++ b/native/jni/src/suggest/core/dicnode/dic_node_release_listener.h
@@ -21,6 +21,8 @@
 
 namespace latinime {
 
+class DicNode;
+
 class DicNodeReleaseListener {
  public:
     DicNodeReleaseListener() {}
diff --git a/native/jni/src/suggest/core/dicnode/dic_node_properties.h b/native/jni/src/suggest/core/dicnode/internal/dic_node_properties.h
similarity index 100%
rename from native/jni/src/suggest/core/dicnode/dic_node_properties.h
rename to native/jni/src/suggest/core/dicnode/internal/dic_node_properties.h
diff --git a/native/jni/src/suggest/core/dicnode/dic_node_state.h b/native/jni/src/suggest/core/dicnode/internal/dic_node_state.h
similarity index 89%
rename from native/jni/src/suggest/core/dicnode/dic_node_state.h
rename to native/jni/src/suggest/core/dicnode/internal/dic_node_state.h
index b1b6266..b0fddb7 100644
--- a/native/jni/src/suggest/core/dicnode/dic_node_state.h
+++ b/native/jni/src/suggest/core/dicnode/internal/dic_node_state.h
@@ -18,10 +18,10 @@
 #define LATINIME_DIC_NODE_STATE_H
 
 #include "defines.h"
-#include "suggest/core/dicnode/dic_node_state_input.h"
-#include "suggest/core/dicnode/dic_node_state_output.h"
-#include "suggest/core/dicnode/dic_node_state_prevword.h"
-#include "suggest/core/dicnode/dic_node_state_scoring.h"
+#include "suggest/core/dicnode/internal/dic_node_state_input.h"
+#include "suggest/core/dicnode/internal/dic_node_state_output.h"
+#include "suggest/core/dicnode/internal/dic_node_state_prevword.h"
+#include "suggest/core/dicnode/internal/dic_node_state_scoring.h"
 
 namespace latinime {
 
diff --git a/native/jni/src/suggest/core/dicnode/dic_node_state_input.h b/native/jni/src/suggest/core/dicnode/internal/dic_node_state_input.h
similarity index 100%
rename from native/jni/src/suggest/core/dicnode/dic_node_state_input.h
rename to native/jni/src/suggest/core/dicnode/internal/dic_node_state_input.h
diff --git a/native/jni/src/suggest/core/dicnode/dic_node_state_output.h b/native/jni/src/suggest/core/dicnode/internal/dic_node_state_output.h
similarity index 100%
rename from native/jni/src/suggest/core/dicnode/dic_node_state_output.h
rename to native/jni/src/suggest/core/dicnode/internal/dic_node_state_output.h
diff --git a/native/jni/src/suggest/core/dicnode/dic_node_state_prevword.h b/native/jni/src/suggest/core/dicnode/internal/dic_node_state_prevword.h
similarity index 100%
rename from native/jni/src/suggest/core/dicnode/dic_node_state_prevword.h
rename to native/jni/src/suggest/core/dicnode/internal/dic_node_state_prevword.h
diff --git a/native/jni/src/suggest/core/dicnode/dic_node_state_scoring.h b/native/jni/src/suggest/core/dicnode/internal/dic_node_state_scoring.h
similarity index 100%
rename from native/jni/src/suggest/core/dicnode/dic_node_state_scoring.h
rename to native/jni/src/suggest/core/dicnode/internal/dic_node_state_scoring.h
diff --git a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
index 48eb08a..7af83d0 100644
--- a/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/personalization/UserHistoryDictionaryTests.java
@@ -90,8 +90,9 @@
             final String locale = "testRandomWords";
             final String fileName = "UserHistoryDictionary." + locale + ".dict";
             dictFile = new File(getContext().getFilesDir(), fileName);
-            final UserHistoryDictionary dict = UserHistoryDictionary.getInstance(getContext(),
-                    locale, mPrefs);
+            final UserHistoryDictionary dict =
+                    PersonalizationDictionaryHelper.getUserHistoryDictionary(
+                            getContext(), locale, mPrefs);
             dict.isTest = true;
 
             addToDict(dict, words);
@@ -141,8 +142,9 @@
             for (int i = 0; i < numberOfLanguageSwitching; i++) {
                 final int index = i % numberOfLanguages;
                 // Switch languages to locales[index].
-                final UserHistoryDictionary dict = UserHistoryDictionary.getInstance(getContext(),
-                        locales[index], mPrefs);
+                final UserHistoryDictionary dict =
+                        PersonalizationDictionaryHelper.getUserHistoryDictionary(
+                                getContext(), locales[index], mPrefs);
                 final List<String> words = generateWords(
                         numberOfWordsIntertedForEachLanguageSwitch, random);
                 // Add random words to the user history dictionary.