diff --git a/java/res/drawable-hdpi/sym_keyboard_smiley_holo_dark.png b/java/res/drawable-hdpi/sym_keyboard_smiley_holo_dark.png
new file mode 100644
index 0000000..cfacbc2
--- /dev/null
+++ b/java/res/drawable-hdpi/sym_keyboard_smiley_holo_dark.png
Binary files differ
diff --git a/java/res/drawable-mdpi/sym_keyboard_smiley_holo_dark.png b/java/res/drawable-mdpi/sym_keyboard_smiley_holo_dark.png
index 71272bb..067ad54 100644
--- a/java/res/drawable-mdpi/sym_keyboard_smiley_holo_dark.png
+++ b/java/res/drawable-mdpi/sym_keyboard_smiley_holo_dark.png
Binary files differ
diff --git a/java/res/drawable-xhdpi/sym_keyboard_smiley_holo_dark.png b/java/res/drawable-xhdpi/sym_keyboard_smiley_holo_dark.png
index 686831f..e6baa2e 100644
--- a/java/res/drawable-xhdpi/sym_keyboard_smiley_holo_dark.png
+++ b/java/res/drawable-xhdpi/sym_keyboard_smiley_holo_dark.png
Binary files differ
diff --git a/java/res/drawable-xxhdpi/sym_keyboard_smiley_holo_dark.png b/java/res/drawable-xxhdpi/sym_keyboard_smiley_holo_dark.png
index 04b7216..5973ac3 100644
--- a/java/res/drawable-xxhdpi/sym_keyboard_smiley_holo_dark.png
+++ b/java/res/drawable-xxhdpi/sym_keyboard_smiley_holo_dark.png
Binary files differ
diff --git a/java/res/layout/emoji_keyboard_tab_icon.xml b/java/res/layout/emoji_keyboard_tab_icon.xml
index d79276e..1609f6a 100644
--- a/java/res/layout/emoji_keyboard_tab_icon.xml
+++ b/java/res/layout/emoji_keyboard_tab_icon.xml
@@ -23,4 +23,5 @@
     android:layout_weight="1.0"
     android:layout_height="wrap_content"
     android:gravity="center"
+    android:scaleType="center"
 />
diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
index a282f59..e901376 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
@@ -288,6 +288,8 @@
         return BinaryDictEncoderUtils.getByteSize(value);
     }
 
+    // TODO: Remove this method.
+    @Deprecated
     static void skipPtNode(final DictBuffer dictBuffer, final FormatOptions formatOptions) {
         final int flags = dictBuffer.readUnsignedByte();
         BinaryDictDecoderUtils.readParentAddress(dictBuffer, formatOptions);
diff --git a/java/src/com/android/inputmethod/latin/makedict/DictDecoder.java b/java/src/com/android/inputmethod/latin/makedict/DictDecoder.java
index 3796a46..e251f7d 100644
--- a/java/src/com/android/inputmethod/latin/makedict/DictDecoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/DictDecoder.java
@@ -391,4 +391,6 @@
             return readLength;
         }
     }
+
+    public abstract void skipPtNode(final FormatOptions formatOptions);
 }
diff --git a/java/src/com/android/inputmethod/latin/makedict/Ver3DictDecoder.java b/java/src/com/android/inputmethod/latin/makedict/Ver3DictDecoder.java
index 848277c..75d1058 100644
--- a/java/src/com/android/inputmethod/latin/makedict/Ver3DictDecoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/Ver3DictDecoder.java
@@ -231,4 +231,40 @@
     public boolean hasNextPtNodeArray() {
         return mDictBuffer.position() != FormatSpec.NO_FORWARD_LINK_ADDRESS;
     }
+
+    @Override
+    public void skipPtNode(final FormatOptions formatOptions) {
+        final int flags = PtNodeReader.readPtNodeOptionFlags(mDictBuffer);
+        PtNodeReader.readParentAddress(mDictBuffer, formatOptions);
+        BinaryDictIOUtils.skipString(mDictBuffer,
+                (flags & FormatSpec.FLAG_HAS_MULTIPLE_CHARS) != 0);
+        PtNodeReader.readChildrenAddress(mDictBuffer, flags, formatOptions);
+        if ((flags & FormatSpec.FLAG_IS_TERMINAL) != 0) PtNodeReader.readFrequency(mDictBuffer);
+        if ((flags & FormatSpec.FLAG_HAS_SHORTCUT_TARGETS) != 0) {
+            final int shortcutsSize = mDictBuffer.readUnsignedShort();
+            mDictBuffer.position(mDictBuffer.position() + shortcutsSize
+                    - FormatSpec.PTNODE_SHORTCUT_LIST_SIZE_SIZE);
+        }
+        if ((flags & FormatSpec.FLAG_HAS_BIGRAMS) != 0) {
+            int bigramCount = 0;
+            while (bigramCount++ < FormatSpec.MAX_BIGRAMS_IN_A_PTNODE) {
+                final int bigramFlags = mDictBuffer.readUnsignedByte();
+                switch (bigramFlags & FormatSpec.MASK_BIGRAM_ATTR_ADDRESS_TYPE) {
+                    case FormatSpec.FLAG_BIGRAM_ATTR_ADDRESS_TYPE_ONEBYTE:
+                        mDictBuffer.readUnsignedByte();
+                        break;
+                    case FormatSpec.FLAG_BIGRAM_ATTR_ADDRESS_TYPE_TWOBYTES:
+                        mDictBuffer.readUnsignedShort();
+                        break;
+                    case FormatSpec.FLAG_BIGRAM_ATTR_ADDRESS_TYPE_THREEBYTES:
+                        mDictBuffer.readUnsignedInt24();
+                        break;
+                }
+                if ((bigramFlags & FormatSpec.FLAG_BIGRAM_SHORTCUT_ATTR_HAS_NEXT) == 0) break;
+            }
+            if (bigramCount >= FormatSpec.MAX_BIGRAMS_IN_A_PTNODE) {
+                throw new RuntimeException("Too many bigrams in a PtNode.");
+            }
+        }
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java b/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
index 0aa4319..fa19e26 100644
--- a/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
@@ -293,4 +293,14 @@
     public boolean hasNextPtNodeArray() {
         return mDictBuffer.position() != FormatSpec.NO_FORWARD_LINK_ADDRESS;
     }
+
+    @Override
+    public void skipPtNode(final FormatOptions formatOptions) {
+        final int flags = PtNodeReader.readPtNodeOptionFlags(mDictBuffer);
+        PtNodeReader.readParentAddress(mDictBuffer, formatOptions);
+        BinaryDictIOUtils.skipString(mDictBuffer,
+                (flags & FormatSpec.FLAG_HAS_MULTIPLE_CHARS) != 0);
+        if ((flags & FormatSpec.FLAG_IS_TERMINAL) != 0) PtNodeReader.readTerminalId(mDictBuffer);
+        PtNodeReader.readChildrenAddress(mDictBuffer, flags, formatOptions);
+    }
 }
diff --git a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
index 21c15ea..38159b0 100644
--- a/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
+++ b/native/jni/com_android_inputmethod_latin_BinaryDictionary.cpp
@@ -344,8 +344,7 @@
     static const int GET_PROPERTY_RESULT_LENGTH = 100;
     char resultChars[GET_PROPERTY_RESULT_LENGTH];
     resultChars[0] = '\0';
-    dictionary->getDictionaryStructurePolicy()->getProperty(queryChars, resultChars,
-            GET_PROPERTY_RESULT_LENGTH);
+    dictionary->getProperty(queryChars, resultChars, GET_PROPERTY_RESULT_LENGTH);
     return env->NewStringUTF(resultChars);
 }
 
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.cpp b/native/jni/src/suggest/core/dictionary/dictionary.cpp
index 5969b31..59ead18 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.cpp
+++ b/native/jni/src/suggest/core/dictionary/dictionary.cpp
@@ -129,7 +129,7 @@
 }
 
 void Dictionary::getProperty(const char *const query, char *const outResult,
-        const int maxResultLength) const {
+        const int maxResultLength) {
     return mDictionaryStructureWithBufferPolicy->getProperty(query, outResult, maxResultLength);
 }
 
diff --git a/native/jni/src/suggest/core/dictionary/dictionary.h b/native/jni/src/suggest/core/dictionary/dictionary.h
index 43d3b96..0195d5b 100644
--- a/native/jni/src/suggest/core/dictionary/dictionary.h
+++ b/native/jni/src/suggest/core/dictionary/dictionary.h
@@ -84,7 +84,7 @@
     bool needsToRunGC(const bool mindsBlockByGC);
 
     void getProperty(const char *const query, char *const outResult,
-            const int maxResultLength) const;
+            const int maxResultLength);
 
     const DictionaryStructureWithBufferPolicy *getDictionaryStructurePolicy() const {
         return mDictionaryStructureWithBufferPolicy;
diff --git a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
index c7ffef0..41f8204 100644
--- a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
+++ b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
@@ -80,8 +80,10 @@
 
     virtual bool needsToRunGC(const bool mindsBlockByGC) const = 0;
 
+    // Currently, this method is used only for testing. You may want to consider creating new
+    // dedicated method instead of this if you want to use this in the production.
     virtual void getProperty(const char *const query, char *const outResult,
-            const int maxResultLength) const = 0;
+            const int maxResultLength) = 0;
 
  protected:
     DictionaryStructureWithBufferPolicy() {}
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
index 0d8c927..a5a42ea 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
@@ -33,12 +33,16 @@
 
 namespace latinime {
 
+// Note that these are corresponding definitions in Java side in BinaryDictionaryTests and
+// BinaryDictionaryDecayingTests.
 const char *const DynamicPatriciaTriePolicy::UNIGRAM_COUNT_QUERY = "UNIGRAM_COUNT";
 const char *const DynamicPatriciaTriePolicy::BIGRAM_COUNT_QUERY = "BIGRAM_COUNT";
+const char *const DynamicPatriciaTriePolicy::SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY =
+        "SET_NEEDS_TO_DECAY_FOR_TESTING";
 const int DynamicPatriciaTriePolicy::MAX_DICT_EXTENDED_REGION_SIZE = 1024 * 1024;
 const int DynamicPatriciaTriePolicy::MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS =
         DynamicPatriciaTrieWritingHelper::MAX_DICTIONARY_SIZE - 1024;
-const int DynamicPatriciaTriePolicy::MIN_SECONDS_TO_REQUIRE_GC_WHEN_WRITING = 2 * 60 * 60;
+const int DynamicPatriciaTriePolicy::DECAY_INTERVAL_FOR_DECAYING_DICTS = 2 * 60 * 60;
 
 void DynamicPatriciaTriePolicy::createAndGetAllChildNodes(const DicNode *const dicNode,
         DicNodeVector *const childDicNodes) const {
@@ -301,7 +305,7 @@
         return;
     }
     DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
-            &mBigramListPolicy, &mShortcutListPolicy, mHeaderPolicy.isDecayingDict());
+            &mBigramListPolicy, &mShortcutListPolicy, false /* needsToDecay */);
     writingHelper.writeToDictFile(filePath, &mHeaderPolicy, mUnigramCount, mBigramCount);
 }
 
@@ -310,9 +314,15 @@
         AKLOGI("Warning: flushWithGC() is called for non-updatable dictionary.");
         return;
     }
+    const bool runGCwithDecay = needsToDecay();
+    DynamicBigramListPolicy bigramListPolicyForGC(&mBufferWithExtendableBuffer,
+            &mShortcutListPolicy, runGCwithDecay);
     DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
-            &mBigramListPolicy, &mShortcutListPolicy, mHeaderPolicy.isDecayingDict());
+            &bigramListPolicyForGC, &mShortcutListPolicy, runGCwithDecay);
     writingHelper.writeToDictFileWithGC(getRootPosition(), filePath, &mHeaderPolicy);
+    if (runGCwithDecay) {
+        mNeedsToDecayForTesting = false;
+    }
 }
 
 bool DynamicPatriciaTriePolicy::needsToRunGC(const bool mindsBlockByGC) const {
@@ -340,8 +350,7 @@
         } else if (mBigramCount >= DecayingUtils::MAX_BIGRAM_COUNT) {
             // Bigram count exceeds the limit.
             return true;
-        } else if (mindsBlockByGC && mHeaderPolicy.getLastUpdatedTime()
-                + MIN_SECONDS_TO_REQUIRE_GC_WHEN_WRITING < time(0)) {
+        } else if (mindsBlockByGC && needsToDecay()) {
             // Time to update probabilities for decaying.
             return true;
         }
@@ -350,12 +359,19 @@
 }
 
 void DynamicPatriciaTriePolicy::getProperty(const char *const query, char *const outResult,
-        const int maxResultLength) const {
+        const int maxResultLength) {
     if (strncmp(query, UNIGRAM_COUNT_QUERY, maxResultLength) == 0) {
         snprintf(outResult, maxResultLength, "%d", mUnigramCount);
     } else if (strncmp(query, BIGRAM_COUNT_QUERY, maxResultLength) == 0) {
         snprintf(outResult, maxResultLength, "%d", mBigramCount);
+    } else if (strncmp(query, SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY, maxResultLength) == 0) {
+        mNeedsToDecayForTesting = true;
     }
 }
 
+bool DynamicPatriciaTriePolicy::needsToDecay() const {
+    return mHeaderPolicy.isDecayingDict() && (mNeedsToDecayForTesting
+            || mHeaderPolicy.getLastDecayedTime() + DECAY_INTERVAL_FOR_DECAYING_DICTS < time(0));
+}
+
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
index d3150c6..c3bbe99 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
@@ -40,7 +40,7 @@
               mBigramListPolicy(&mBufferWithExtendableBuffer, &mShortcutListPolicy,
                       mHeaderPolicy.isDecayingDict()),
               mUnigramCount(mHeaderPolicy.getUnigramCount()),
-              mBigramCount(mHeaderPolicy.getBigramCount()) {}
+              mBigramCount(mHeaderPolicy.getBigramCount()), mNeedsToDecayForTesting(false) {}
 
     ~DynamicPatriciaTriePolicy() {
         delete mBuffer;
@@ -95,16 +95,17 @@
     bool needsToRunGC(const bool mindsBlockByGC) const;
 
     void getProperty(const char *const query, char *const outResult,
-            const int maxResultLength) const;
+            const int maxResultLength);
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicPatriciaTriePolicy);
 
-    static const char*const UNIGRAM_COUNT_QUERY;
-    static const char*const BIGRAM_COUNT_QUERY;
+    static const char *const UNIGRAM_COUNT_QUERY;
+    static const char *const BIGRAM_COUNT_QUERY;
+    static const char *const SET_NEEDS_TO_DECAY_FOR_TESTING_QUERY;
     static const int MAX_DICT_EXTENDED_REGION_SIZE;
     static const int MIN_DICT_SIZE_TO_REFUSE_DYNAMIC_OPERATIONS;
-    static const int MIN_SECONDS_TO_REQUIRE_GC_WHEN_WRITING;
+    static const int DECAY_INTERVAL_FOR_DECAYING_DICTS;
 
     const MmappedBuffer *const mBuffer;
     const HeaderPolicy mHeaderPolicy;
@@ -113,6 +114,9 @@
     DynamicBigramListPolicy mBigramListPolicy;
     int mUnigramCount;
     int mBigramCount;
+    int mNeedsToDecayForTesting;
+
+    bool needsToDecay() const;
 };
 } // namespace latinime
 #endif // LATINIME_DYNAMIC_PATRICIA_TRIE_POLICY_H
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
index 28124d2..db6d48f 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
@@ -153,7 +153,7 @@
     const int extendedRegionSize = headerPolicy->getExtendedRegionSize() +
             mBuffer->getUsedAdditionalBufferSize();
     if (!headerPolicy->writeHeaderToBuffer(&headerBuffer, false /* updatesLastUpdatedTime */,
-            unigramCount, bigramCount, extendedRegionSize)) {
+            false /* updatesLastDecayedTime */, unigramCount, bigramCount, extendedRegionSize)) {
         return;
     }
     DictFileWritingUtils::flushAllHeaderAndBodyToFile(fileName, &headerBuffer, mBuffer);
@@ -170,7 +170,7 @@
     }
     BufferWithExtendableBuffer headerBuffer(0 /* originalBuffer */, 0 /* originalBufferSize */);
     if (!headerPolicy->writeHeaderToBuffer(&headerBuffer, true /* updatesLastUpdatedTime */,
-            unigramCount, bigramCount, 0 /* extendedRegionSize */)) {
+            mNeedsToDecay, unigramCount, bigramCount, 0 /* extendedRegionSize */)) {
         return;
     }
     DictFileWritingUtils::flushAllHeaderAndBodyToFile(fileName, &headerBuffer, &newDictBuffer);
@@ -488,12 +488,12 @@
     DynamicPatriciaTrieGcEventListeners
             ::TraversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted
                     traversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted(
-                            this, mBuffer, mIsDecayingDict);
+                            this, mBuffer, mNeedsToDecay);
     if (!readingHelper.traverseAllPtNodesInPostorderDepthFirstManner(
             &traversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted)) {
         return false;
     }
-    if (mIsDecayingDict && traversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted
+    if (mNeedsToDecay && traversePolicyToUpdateUnigramProbabilityAndMarkUselessPtNodesAsDeleted
             .getValidUnigramCount() > DecayingUtils::MAX_UNIGRAM_COUNT_AFTER_GC) {
         // TODO: Remove more unigrams.
     }
@@ -506,7 +506,7 @@
         return false;
     }
 
-    if (mIsDecayingDict && traversePolicyToUpdateBigramProbability.getValidBigramEntryCount()
+    if (mNeedsToDecay && traversePolicyToUpdateBigramProbability.getValidBigramEntryCount()
             > DecayingUtils::MAX_BIGRAM_COUNT_AFTER_GC) {
         // TODO: Remove more bigrams.
     }
@@ -525,7 +525,7 @@
     // Create policy instance for the GCed dictionary.
     DynamicShortcutListPolicy newDictShortcutPolicy(bufferToWrite);
     DynamicBigramListPolicy newDictBigramPolicy(bufferToWrite, &newDictShortcutPolicy,
-            mIsDecayingDict);
+            mNeedsToDecay);
     // Create reading helper for the GCed dictionary.
     DynamicPatriciaTrieReadingHelper newDictReadingHelper(bufferToWrite, &newDictBigramPolicy,
             &newDictShortcutPolicy);
@@ -544,7 +544,7 @@
 
 int DynamicPatriciaTrieWritingHelper::getUpdatedProbability(const int originalProbability,
         const int newProbability) {
-    if (mIsDecayingDict) {
+    if (mNeedsToDecay) {
         return DecayingUtils::getUpdatedUnigramProbability(originalProbability, newProbability);
     } else {
         return newProbability;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
index ecee2cd..0caf291 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
@@ -51,9 +51,9 @@
 
     DynamicPatriciaTrieWritingHelper(BufferWithExtendableBuffer *const buffer,
             DynamicBigramListPolicy *const bigramPolicy,
-            DynamicShortcutListPolicy *const shortcutPolicy, const bool isDecayingDict)
+            DynamicShortcutListPolicy *const shortcutPolicy, const bool needsToDecay)
             : mBuffer(buffer), mBigramPolicy(bigramPolicy), mShortcutPolicy(shortcutPolicy),
-              mIsDecayingDict(isDecayingDict) {}
+              mNeedsToDecay(needsToDecay) {}
 
     ~DynamicPatriciaTrieWritingHelper() {}
 
@@ -94,7 +94,7 @@
     BufferWithExtendableBuffer *const mBuffer;
     DynamicBigramListPolicy *const mBigramPolicy;
     DynamicShortcutListPolicy *const mShortcutPolicy;
-    const bool mIsDecayingDict;
+    const bool mNeedsToDecay;
 
     bool markNodeAsMovedAndSetPosition(const DynamicPatriciaTrieNodeReader *const nodeToUpdate,
             const int movedPos, const int bigramLinkedNodePos);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
index 9ce9994..eb072fb 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.cpp
@@ -23,6 +23,7 @@
 // TODO: Change attribute string to "IS_DECAYING_DICT".
 const char *const HeaderPolicy::IS_DECAYING_DICT_KEY = "USES_FORGETTING_CURVE";
 const char *const HeaderPolicy::LAST_UPDATED_TIME_KEY = "date";
+const char *const HeaderPolicy::LAST_DECAYED_TIME_KEY = "LAST_DECAYED_TIME";
 const char *const HeaderPolicy::UNIGRAM_COUNT_KEY = "UNIGRAM_COUNT";
 const char *const HeaderPolicy::BIGRAM_COUNT_KEY = "BIGRAM_COUNT";
 const char *const HeaderPolicy::EXTENDED_REGION_SIZE_KEY = "EXTENDED_REGION_SIZE";
@@ -63,8 +64,8 @@
 }
 
 bool HeaderPolicy::writeHeaderToBuffer(BufferWithExtendableBuffer *const bufferToWrite,
-        const bool updatesLastUpdatedTime, const int unigramCount, const int bigramCount,
-        const int extendedRegionSize) const {
+        const bool updatesLastUpdatedTime, const bool updatesLastDecayedTime,
+        const int unigramCount, const int bigramCount, const int extendedRegionSize) const {
     int writingPos = 0;
     if (!HeaderReadWriteUtils::writeDictionaryVersion(bufferToWrite, mDictFormatVersion,
             &writingPos)) {
@@ -90,6 +91,11 @@
         HeaderReadWriteUtils::setIntAttribute(&attributeMapTowrite, LAST_UPDATED_TIME_KEY,
                 time(0));
     }
+    if (updatesLastDecayedTime) {
+        // Set current time as a last updated time.
+        HeaderReadWriteUtils::setIntAttribute(&attributeMapTowrite, LAST_DECAYED_TIME_KEY,
+                time(0));
+    }
     if (!HeaderReadWriteUtils::writeHeaderAttributes(bufferToWrite, &attributeMapTowrite,
             &writingPos)) {
         return false;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
index 4261667..a9c7805 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/header/header_policy.h
@@ -40,6 +40,8 @@
                       IS_DECAYING_DICT_KEY, false /* defaultValue */)),
               mLastUpdatedTime(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
                       LAST_UPDATED_TIME_KEY, time(0) /* defaultValue */)),
+              mLastDecayedTime(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
+                      LAST_DECAYED_TIME_KEY, time(0) /* defaultValue */)),
               mUnigramCount(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
                       UNIGRAM_COUNT_KEY, 0 /* defaultValue */)),
               mBigramCount(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
@@ -58,6 +60,8 @@
                       IS_DECAYING_DICT_KEY, false /* defaultValue */)),
               mLastUpdatedTime(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
                       LAST_UPDATED_TIME_KEY, time(0) /* defaultValue */)),
+              mLastDecayedTime(HeaderReadWriteUtils::readIntAttributeValue(&mAttributeMap,
+                      LAST_UPDATED_TIME_KEY, time(0) /* defaultValue */)),
               mUnigramCount(0), mBigramCount(0), mExtendedRegionSize(0) {}
 
     ~HeaderPolicy() {}
@@ -90,6 +94,10 @@
         return mLastUpdatedTime;
     }
 
+    AK_FORCE_INLINE int getLastDecayedTime() const {
+        return mLastDecayedTime;
+    }
+
     AK_FORCE_INLINE int getUnigramCount() const {
         return mUnigramCount;
     }
@@ -106,8 +114,8 @@
             int *outValue, int outValueSize) const;
 
     bool writeHeaderToBuffer(BufferWithExtendableBuffer *const bufferToWrite,
-            const bool updatesLastUpdatedTime, const int unigramCount,
-            const int bigramCount, const int extendedRegionSize) const;
+            const bool updatesLastUpdatedTime, const bool updatesLastDecayedTime,
+            const int unigramCount, const int bigramCount, const int extendedRegionSize) const;
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(HeaderPolicy);
@@ -115,6 +123,7 @@
     static const char *const MULTIPLE_WORDS_DEMOTION_RATE_KEY;
     static const char *const IS_DECAYING_DICT_KEY;
     static const char *const LAST_UPDATED_TIME_KEY;
+    static const char *const LAST_DECAYED_TIME_KEY;
     static const char *const UNIGRAM_COUNT_KEY;
     static const char *const BIGRAM_COUNT_KEY;
     static const char *const EXTENDED_REGION_SIZE_KEY;
@@ -128,6 +137,7 @@
     const float mMultiWordCostMultiplier;
     const bool mIsDecayingDict;
     const int mLastUpdatedTime;
+    const int mLastDecayedTime;
     const int mUnigramCount;
     const int mBigramCount;
     const int mExtendedRegionSize;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
index 8d88c68..0f8662a 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/patricia_trie_policy.h
@@ -114,7 +114,7 @@
     }
 
     void getProperty(const char *const query, char *const outResult,
-            const int maxResultLength) const {
+            const int maxResultLength) {
         // getProperty is not supported for this class.
         if (maxResultLength > 0) {
             outResult[0] = '\0';
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.cpp b/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.cpp
index f22e94c..994826f 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/dict_file_writing_utils.cpp
@@ -44,7 +44,8 @@
     BufferWithExtendableBuffer headerBuffer(0 /* originalBuffer */, 0 /* originalBufferSize */);
     HeaderPolicy headerPolicy(FormatUtils::VERSION_3, attributeMap);
     headerPolicy.writeHeaderToBuffer(&headerBuffer, true /* updatesLastUpdatedTime */,
-            0 /* unigramCount */, 0 /* bigramCount */, 0 /* extendedRegionSize */);
+            true /* updatesLastDecayedTime */, 0 /* unigramCount */, 0 /* bigramCount */,
+            0 /* extendedRegionSize */);
     BufferWithExtendableBuffer bodyBuffer(0 /* originalBuffer */, 0 /* originalBufferSize */);
     if (!DynamicPatriciaTrieWritingUtils::writeEmptyDictionary(&bodyBuffer, 0 /* rootPos */)) {
         return false;
diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
index cf85d97..8a439fc 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryDecayingTests.java
@@ -32,6 +32,11 @@
     private static final String TEST_DICT_FILE_EXTENSION = ".testDict";
     private static final String TEST_LOCALE = "test";
 
+    // Note that these are corresponding definitions in native code in
+    // latinime::DynamicPatriciaTriePolicy.
+    private static final String SET_NEEDS_TO_DECAY_FOR_TESTING_KEY =
+            "SET_NEEDS_TO_DECAY_FOR_TESTING";
+
     private static final int DUMMY_PROBABILITY = 0;
 
     @Override
@@ -45,6 +50,7 @@
     }
 
     private void forcePassingShortTime(final BinaryDictionary binaryDictionary) {
+        binaryDictionary.getPropertyForTests(SET_NEEDS_TO_DECAY_FOR_TESTING_KEY);
         binaryDictionary.flushWithGC();
     }
 
@@ -53,6 +59,7 @@
         // typed in 32 GCs are removed.
         final int count = 32;
         for (int i = 0; i < count; i++) {
+            binaryDictionary.getPropertyForTests(SET_NEEDS_TO_DECAY_FOR_TESTING_KEY);
             binaryDictionary.flushWithGC();
         }
     }