diff --git a/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java b/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
index 5864db2..2601551 100644
--- a/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
+++ b/java/src/com/android/inputmethod/latin/makedict/FusionDictionary.java
@@ -516,13 +516,22 @@
             int indexOfGroup = findIndexOfChar(node, s.codePointAt(index));
             if (CHARACTER_NOT_FOUND == indexOfGroup) return null;
             currentGroup = node.mData.get(indexOfGroup);
+
+            if (s.length() - index < currentGroup.mChars.length) return null;
+            int newIndex = index;
+            while (newIndex < s.length() && newIndex - index < currentGroup.mChars.length) {
+                if (currentGroup.mChars[newIndex - index] != s.codePointAt(newIndex)) return null;
+                newIndex++;
+            }
+            index = newIndex;
+
             if (DBG) checker.append(new String(currentGroup.mChars, 0, currentGroup.mChars.length));
-            index += currentGroup.mChars.length;
             if (index < s.length()) {
                 node = currentGroup.mChildren;
             }
         } while (null != node && index < s.length());
 
+        if (index < s.length()) return null;
         if (DBG && !s.equals(checker.toString())) return null;
         return currentGroup;
     }
diff --git a/tests/src/com/android/inputmethod/latin/FusionDictionaryTests.java b/tests/src/com/android/inputmethod/latin/FusionDictionaryTests.java
new file mode 100644
index 0000000..e3f7583
--- /dev/null
+++ b/tests/src/com/android/inputmethod/latin/FusionDictionaryTests.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2012 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 android.test.AndroidTestCase;
+
+import com.android.inputmethod.latin.makedict.FusionDictionary;
+import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
+
+import java.util.HashMap;
+
+/**
+ * Unit test for FusionDictionary
+ */
+public class FusionDictionaryTests extends AndroidTestCase {
+    public void testFindWordInTree() {
+        FusionDictionary dict = new FusionDictionary(new Node(),
+                new FusionDictionary.DictionaryOptions(new HashMap<String,String>(), false, false));
+
+        dict.add("abc", 10, null);
+        assertNull(FusionDictionary.findWordInTree(dict.mRoot, "aaa"));
+        assertNotNull(FusionDictionary.findWordInTree(dict.mRoot, "abc"));
+
+        dict.add("aa", 10, null);
+        assertNull(FusionDictionary.findWordInTree(dict.mRoot, "aaa"));
+        assertNotNull(FusionDictionary.findWordInTree(dict.mRoot, "aa"));
+    }
+}