diff --git a/native/jni/NativeFileList.mk b/native/jni/NativeFileList.mk
index fe21061..1cb61c4 100644
--- a/native/jni/NativeFileList.mk
+++ b/native/jni/NativeFileList.mk
@@ -124,4 +124,5 @@
     defines_test.cpp \
     suggest/core/layout/normal_distribution_2d_test.cpp \
     suggest/core/dictionary/bloom_filter_test.cpp \
+    suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer_test.cpp \
     utils/autocorrection_threshold_utils_test.cpp
diff --git a/native/jni/src/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp b/native/jni/src/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
index fab7208..825b72c 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.cpp
@@ -102,8 +102,9 @@
 
 bool BufferWithExtendableBuffer::extendBuffer(const size_t size) {
     const size_t extendSize = std::max(EXTEND_ADDITIONAL_BUFFER_SIZE_STEP, size);
-    const size_t sizeAfterExtending = mAdditionalBuffer.size() + extendSize;
-    if (sizeAfterExtending > mMaxAdditionalBufferSize) {
+    const size_t sizeAfterExtending =
+            std::min(mAdditionalBuffer.size() + extendSize, mMaxAdditionalBufferSize);
+    if (sizeAfterExtending < mAdditionalBuffer.size() + size) {
         return false;
     }
     mAdditionalBuffer.resize(sizeAfterExtending);
diff --git a/native/jni/tests/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer_test.cpp b/native/jni/tests/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer_test.cpp
new file mode 100644
index 0000000..fa6c6d7
--- /dev/null
+++ b/native/jni/tests/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer_test.cpp
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
+
+#include <gtest/gtest.h>
+
+namespace latinime {
+namespace {
+
+const int DEFAULT_MAX_BUFFER_SIZE = 1024;
+
+TEST(BufferWithExtendablebufferTest, TestWriteAndRead) {
+    BufferWithExtendableBuffer buffer(DEFAULT_MAX_BUFFER_SIZE);
+    int pos = 0;
+    // 1 byte
+    const uint32_t data_1 = 0xFF;
+    EXPECT_TRUE(buffer.writeUint(data_1, 1 /* size */, pos));
+    EXPECT_EQ(data_1, buffer.readUint(1, pos));
+    pos += 1;
+    // 2 byte
+    const uint32_t data_2 = 0xFFFF;
+    EXPECT_TRUE(buffer.writeUint(data_2, 2 /* size */, pos));
+    EXPECT_EQ(data_2, buffer.readUint(2, pos));
+    pos += 2;
+    // 3 byte
+    const uint32_t data_3 = 0xFFFFFF;
+    EXPECT_TRUE(buffer.writeUint(data_3, 3 /* size */, pos));
+    EXPECT_EQ(data_3, buffer.readUint(3, pos));
+    pos += 3;
+    // 4 byte
+    const uint32_t data_4 = 0xFFFFFFFF;
+    EXPECT_TRUE(buffer.writeUint(data_4, 4 /* size */, pos));
+    EXPECT_EQ(data_4, buffer.readUint(4, pos));
+}
+
+TEST(BufferWithExtendablebufferTest, TestExtend) {
+    BufferWithExtendableBuffer buffer(DEFAULT_MAX_BUFFER_SIZE);
+    EXPECT_EQ(0, buffer.getTailPosition());
+    EXPECT_TRUE(buffer.writeUint(0xFF /* data */, 4 /* size */, 0 /* pos */));
+    EXPECT_EQ(4, buffer.getTailPosition());
+    EXPECT_TRUE(buffer.extend(8 /* size */));
+    EXPECT_EQ(12, buffer.getTailPosition());
+    EXPECT_TRUE(buffer.writeUint(0xFFFF /* data */, 4 /* size */, 8 /* pos */));
+    EXPECT_TRUE(buffer.writeUint(0xFF /* data */, 4 /* size */, 0 /* pos */));
+}
+
+TEST(BufferWithExtendablebufferTest, TestCopy) {
+    BufferWithExtendableBuffer buffer(DEFAULT_MAX_BUFFER_SIZE);
+    EXPECT_TRUE(buffer.writeUint(0xFF /* data */, 4 /* size */, 0 /* pos */));
+    EXPECT_TRUE(buffer.writeUint(0xFFFF /* data */, 4 /* size */, 4 /* pos */));
+    BufferWithExtendableBuffer targetBuffer(DEFAULT_MAX_BUFFER_SIZE);
+    EXPECT_TRUE(targetBuffer.copy(&buffer));
+    EXPECT_EQ(0xFFu, targetBuffer.readUint(4 /* size */, 0 /* pos */));
+    EXPECT_EQ(0xFFFFu, targetBuffer.readUint(4 /* size */, 4 /* pos */));
+}
+
+TEST(BufferWithExtendablebufferTest, TestSizeLimit) {
+    BufferWithExtendableBuffer emptyBuffer(0 /* maxAdditionalBufferSize */);
+    EXPECT_FALSE(emptyBuffer.writeUint(0 /* data */, 1 /* size */, 0 /* pos */));
+    EXPECT_FALSE(emptyBuffer.extend(1 /* size */));
+
+    BufferWithExtendableBuffer smallBuffer(4 /* maxAdditionalBufferSize */);
+    EXPECT_TRUE(smallBuffer.writeUint(0 /* data */, 4 /* size */, 0 /* pos */));
+    EXPECT_FALSE(smallBuffer.writeUint(0 /* data */, 1 /* size */, 4 /* pos */));
+
+    EXPECT_TRUE(smallBuffer.copy(&emptyBuffer));
+    EXPECT_FALSE(emptyBuffer.copy(&smallBuffer));
+
+    BufferWithExtendableBuffer buffer(DEFAULT_MAX_BUFFER_SIZE);
+    EXPECT_FALSE(buffer.isNearSizeLimit());
+    int pos = 0;
+    while (!buffer.isNearSizeLimit()) {
+        EXPECT_TRUE(buffer.writeUintAndAdvancePosition(0 /* data */, 4 /* size */, &pos));
+    }
+    EXPECT_GT(pos, 0);
+    EXPECT_LE(pos, DEFAULT_MAX_BUFFER_SIZE);
+}
+
+}  // namespace
+}  // namespace latinime