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 3cfbfd8..2198a13 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
@@ -248,7 +248,9 @@
         AKLOGI("Warning: flush() is called for non-updatable dictionary.");
         return;
     }
-    // TODO: Implement.
+    DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
+            &mBigramListPolicy, &mShortcutListPolicy);
+    writingHelper.writeToDictFile(filePath, mBuffer->getBuffer(), mHeaderPolicy.getSize());
 }
 
 void DynamicPatriciaTriePolicy::flushWithGC(const char *const filePath) {
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 311d31e..a67c0d9 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
@@ -16,6 +16,9 @@
 
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h"
 
+#include <cstdio>
+#include <cstring>
+
 #include "suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h"
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.h"
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h"
@@ -27,6 +30,8 @@
 namespace latinime {
 
 const int DynamicPatriciaTrieWritingHelper::CHILDREN_POSITION_FIELD_SIZE = 3;
+const char *const DynamicPatriciaTrieWritingHelper::TEMP_FILE_SUFFIX_FOR_WRITING_DICT_FILE =
+        ".tmp";
 
 bool DynamicPatriciaTrieWritingHelper::addUnigramWord(
         DynamicPatriciaTrieReadingHelper *const readingHelper,
@@ -131,6 +136,41 @@
     return mBigramPolicy->removeBigram(nodeReader.getBigramsPos(), word1Pos);
 }
 
+void DynamicPatriciaTrieWritingHelper::writeToDictFile(const char *const fileName,
+        const uint8_t *const headerBuf, const int headerSize) {
+    const int tmpFileNameBufSize = strlen(fileName)
+            + strlen(TEMP_FILE_SUFFIX_FOR_WRITING_DICT_FILE) + 1;
+    char tmpFileName[tmpFileNameBufSize];
+    snprintf(tmpFileName, tmpFileNameBufSize, "%s%s", fileName,
+            TEMP_FILE_SUFFIX_FOR_WRITING_DICT_FILE);
+    FILE *const file = fopen(tmpFileName, "wb");
+    if (!file) {
+        return;
+    }
+    // Write header.
+    if (fwrite(headerBuf, headerSize, 1, file) < 1) {
+        fclose(file);
+        remove(tmpFileName);
+        return;
+    }
+    // Write data in original buffer.
+    if (fwrite(mBuffer->getBuffer(false /* usesAdditionalBuffer */),
+            mBuffer->getOriginalBufferSize(), 1, file) < 1) {
+        fclose(file);
+        remove(tmpFileName);
+        return;
+    }
+    // Write data in additional buffer.
+    if (fwrite(mBuffer->getBuffer(true /* usesAdditionalBuffer */),
+            mBuffer->getTailPosition() - mBuffer->getOriginalBufferSize(), 1, file) < 1) {
+        fclose(file);
+        remove(tmpFileName);
+        return;
+    }
+    fclose(file);
+    rename(tmpFileName, fileName);
+}
+
 bool DynamicPatriciaTrieWritingHelper::markNodeAsMovedAndSetPosition(
         const DynamicPatriciaTrieNodeReader *const originalNode, const int movedPos,
         const int bigramLinkedNodePos) {
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 20e35ab..faf7a4e 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
@@ -17,6 +17,8 @@
 #ifndef LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H
 #define LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H
 
+#include <stdint.h>
+
 #include "defines.h"
 
 namespace latinime {
@@ -46,10 +48,14 @@
     // Remove a bigram relation from word0Pos to word1Pos.
     bool removeBigramWords(const int word0Pos, const int word1Pos);
 
+    void writeToDictFile(const char *const fileName, const uint8_t *const headerBuf,
+            const int headerSize);
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicPatriciaTrieWritingHelper);
 
     static const int CHILDREN_POSITION_FIELD_SIZE;
+    static const char *const TEMP_FILE_SUFFIX_FOR_WRITING_DICT_FILE;
 
     BufferWithExtendableBuffer *const mBuffer;
     DynamicBigramListPolicy *const mBigramPolicy;
diff --git a/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java b/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
index 739aedc..d8105ba 100644
--- a/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
+++ b/tests/src/com/android/inputmethod/latin/BinaryDictionaryTests.java
@@ -299,7 +299,6 @@
         BinaryDictionary binaryDictionary = new BinaryDictionary(dictFile.getAbsolutePath(),
                 0 /* offset */, dictFile.length(), true /* useFullEditDistance */,
                 Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
-
         final int unigramProbability = 100;
         final int bigramProbability = 10;
         binaryDictionary.addUnigramWord("aaa", unigramProbability);
@@ -335,4 +334,54 @@
 
         dictFile.delete();
     }
+
+    public void testFlushDictionary() {
+        File dictFile = null;
+        try {
+            dictFile = createEmptyDictionaryAndGetFile("TestBinaryDictionary");
+        } catch (IOException e) {
+            fail("IOException while writing an initial dictionary : " + e);
+        } catch (UnsupportedFormatException e) {
+            fail("UnsupportedFormatException while writing an initial dictionary : " + e);
+        }
+        BinaryDictionary binaryDictionary = new BinaryDictionary(dictFile.getAbsolutePath(),
+                0 /* offset */, dictFile.length(), true /* useFullEditDistance */,
+                Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
+
+        final int probability = 100;
+        binaryDictionary.addUnigramWord("aaa", probability);
+        binaryDictionary.addUnigramWord("abcd", probability);
+        // Close without flushing.
+        binaryDictionary.close();
+
+        binaryDictionary = new BinaryDictionary(dictFile.getAbsolutePath(),
+                0 /* offset */, dictFile.length(), true /* useFullEditDistance */,
+                Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
+
+        assertEquals(-1, binaryDictionary.getFrequency("aaa"));
+        assertEquals(-1, binaryDictionary.getFrequency("abcd"));
+
+        binaryDictionary.addUnigramWord("aaa", probability);
+        binaryDictionary.addUnigramWord("abcd", probability);
+        binaryDictionary.flush();
+        binaryDictionary.close();
+
+        binaryDictionary = new BinaryDictionary(dictFile.getAbsolutePath(),
+                0 /* offset */, dictFile.length(), true /* useFullEditDistance */,
+                Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
+
+        assertEquals(probability, binaryDictionary.getFrequency("aaa"));
+        assertEquals(probability, binaryDictionary.getFrequency("abcd"));
+        binaryDictionary.addUnigramWord("bcde", probability);
+        binaryDictionary.flush();
+        binaryDictionary.close();
+
+        binaryDictionary = new BinaryDictionary(dictFile.getAbsolutePath(),
+                0 /* offset */, dictFile.length(), true /* useFullEditDistance */,
+                Locale.getDefault(), TEST_LOCALE, true /* isUpdatable */);
+        assertEquals(probability, binaryDictionary.getFrequency("bcde"));
+        binaryDictionary.close();
+
+        dictFile.delete();
+    }
 }