diff --git a/native/dicttoolkit/Android.mk b/native/dicttoolkit/Android.mk
index 4befecf..7a44686 100644
--- a/native/dicttoolkit/Android.mk
+++ b/native/dicttoolkit/Android.mk
@@ -51,7 +51,6 @@
 LOCAL_MODULE := dicttoolkit
 LOCAL_MODULE_TAGS := optional
 
-LOCAL_CLANG := true
 LOCAL_CXX_STL := libc++
 
 include $(BUILD_HOST_EXECUTABLE)
diff --git a/native/dicttoolkit/UnitTests.mk b/native/dicttoolkit/UnitTests.mk
index da1b376..55177c0 100644
--- a/native/dicttoolkit/UnitTests.mk
+++ b/native/dicttoolkit/UnitTests.mk
@@ -31,7 +31,6 @@
 LATIN_IME_SRC_DIR := src
 LOCAL_ADDRESS_SANITIZER := true
 LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function
-LOCAL_CLANG := true
 LOCAL_CXX_STL := libc++
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(LATIN_IME_DICT_TOOLKIT_SRC_DIR) \
     $(LATIN_IME_CORE_PATH)/$(LATIN_IME_CORE_SRC_DIR)
@@ -46,7 +45,6 @@
 
 LOCAL_ADDRESS_SANITIZER := true
 LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function
-LOCAL_CLANG := true
 LOCAL_CXX_STL := libc++
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(LATIN_IME_DICT_TOOLKIT_SRC_DIR) \
     $(LATIN_IME_CORE_PATH)/$(LATIN_IME_CORE_SRC_DIR)
diff --git a/native/jni/Android.mk b/native/jni/Android.mk
index 6003a6f..5384648 100644
--- a/native/jni/Android.mk
+++ b/native/jni/Android.mk
@@ -63,7 +63,6 @@
 LOCAL_MODULE := libjni_latinime_common_static
 LOCAL_MODULE_TAGS := optional
 
-LOCAL_CLANG := true
 LOCAL_SDK_VERSION := 14
 LOCAL_NDK_STL_VARIANT := c++_static
 
@@ -87,9 +86,9 @@
 LOCAL_MODULE := libjni_latinime
 LOCAL_MODULE_TAGS := optional
 
-LOCAL_CLANG := true
 LOCAL_SDK_VERSION := 14
 LOCAL_NDK_STL_VARIANT := c++_static
+LOCAL_CFLAGS := -Wall -Werror
 LOCAL_LDFLAGS += -ldl
 
 include $(BUILD_SHARED_LIBRARY)
@@ -101,3 +100,4 @@
 
 #################### Unit test on target environment
 include $(LOCAL_PATH)/TargetUnitTests.mk
+//LOCAL_CFLAGS += -Wall -Werror
diff --git a/native/jni/HostUnitTests.mk b/native/jni/HostUnitTests.mk
index 6a8bcec..94cd764 100644
--- a/native/jni/HostUnitTests.mk
+++ b/native/jni/HostUnitTests.mk
@@ -29,8 +29,7 @@
 #################### Host library for unit test
 LATIN_IME_SRC_DIR := src
 LOCAL_ADDRESS_SANITIZER := true
-LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function
-LOCAL_CLANG := true
+LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function -Wall -Werror
 LOCAL_CXX_STL := libc++
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(LATIN_IME_SRC_DIR)
 LOCAL_MODULE := liblatinime_host_static_for_unittests
@@ -43,7 +42,7 @@
 LATIN_IME_TEST_SRC_DIR := tests
 LOCAL_ADDRESS_SANITIZER := true
 LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function
-LOCAL_CLANG := true
+LOCAL_CFLAGS += -Wall -Werror
 LOCAL_CXX_STL := libc++
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(LATIN_IME_SRC_DIR)
 LOCAL_MODULE := liblatinime_host_unittests
diff --git a/native/jni/TargetUnitTests.mk b/native/jni/TargetUnitTests.mk
index 69a32ed..32aada0 100644
--- a/native/jni/TargetUnitTests.mk
+++ b/native/jni/TargetUnitTests.mk
@@ -21,8 +21,7 @@
 
 #################### Target library for unit test
 LATIN_IME_SRC_DIR := src
-LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function
-LOCAL_CLANG := true
+LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function -Wall -Werror
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(LATIN_IME_SRC_DIR)
 LOCAL_MODULE := liblatinime_target_static_for_unittests
 LOCAL_MODULE_TAGS := optional
@@ -34,8 +33,7 @@
 #################### Target native tests
 include $(CLEAR_VARS)
 LATIN_IME_TEST_SRC_DIR := tests
-LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function
-LOCAL_CLANG := true
+LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function -Wall -Werror
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/$(LATIN_IME_SRC_DIR)
 LOCAL_MODULE := liblatinime_target_unittests
 LOCAL_MODULE_TAGS := tests
diff --git a/native/jni/tests/dictionary/utils/trie_map_test.cpp b/native/jni/tests/dictionary/utils/trie_map_test.cpp
index 745d398..8f3ec9d 100644
--- a/native/jni/tests/dictionary/utils/trie_map_test.cpp
+++ b/native/jni/tests/dictionary/utils/trie_map_test.cpp
@@ -55,6 +55,7 @@
     EXPECT_TRUE(trieMap.remove(10, trieMap.getRootBitmapEntryIndex()));
     EXPECT_FALSE(trieMap.getRoot(10).mIsValid);
     for (const auto &element : trieMap.getEntriesInRootLevel()) {
+        (void)element; // not used
         EXPECT_TRUE(false);
     }
     EXPECT_TRUE(trieMap.putRoot(10, 0x3FFFFF));
diff --git a/tests/Android.mk b/tests/Android.mk
index 998c1de..7c0bb4f 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -28,7 +28,11 @@
     android-support-test \
     mockito-target-minus-junit4
 
-LOCAL_JAVA_LIBRARIES := android.test.mock.sdk legacy-android-test
+LOCAL_JAVA_LIBRARIES := \
+    android.test.mock.stubs \
+    android.test.runner.stubs \
+    android.test.base.stubs \
+
 
 # Include all test java files.
 LOCAL_SRC_FILES := $(call all-java-files-under, src)
diff --git a/tools/dicttool/Android.mk b/tools/dicttool/Android.mk
index 6852b82..4981629 100644
--- a/tools/dicttool/Android.mk
+++ b/tools/dicttool/Android.mk
@@ -16,12 +16,6 @@
 # Only build if it's explicitly requested, or running mm/mmm.
 ifneq ($(ONE_SHOT_MAKEFILE)$(filter $(MAKECMDGOALS),dicttool_aosp),)
 
-# HACK: Temporarily disable host tool build on Mac until the build system is ready for C++11.
-LATINIME_HOST_OSNAME := $(shell uname -s)
-ifeq ($(LATINIME_HOST_OSNAME), Darwin) # TODO: Remove this
-$(warning dicttool_aosp is not supported on $(LATINIME_HOST_OSNAME))
-else # TODO: Remove this
-
 LATINIME_DICTTOOL_AOSP_LOCAL_PATH := $(call my-dir)
 LOCAL_PATH := $(LATINIME_DICTTOOL_AOSP_LOCAL_PATH)
 LATINIME_HOST_NATIVE_LIBNAME := liblatinime-aosp-dicttool-host
@@ -86,11 +80,8 @@
 include $(BUILD_HOST_JAVA_LIBRARY)
 include $(LOCAL_PATH)/etc/Android.mk
 
-endif # Darwin - TODO: Remove this
-
 # Clear our private variables
 LATINIME_DICTTOOL_AOSP_LOCAL_PATH :=
 LATINIME_LOCAL_DIR :=
-LATINIME_HOST_OSNAME :=
 
 endif
diff --git a/tools/dicttool/NativeLib.mk b/tools/dicttool/NativeLib.mk
index 622a9f1..510f18c 100644
--- a/tools/dicttool/NativeLib.mk
+++ b/tools/dicttool/NativeLib.mk
@@ -13,10 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# HACK: Temporarily disable host tool build on Mac until the build system is ready for C++11.
-LATINIME_HOST_OSNAME := $(shell uname -s)
-ifneq ($(LATINIME_HOST_OSNAME), Darwin) # TODO: Remove this
-
 LOCAL_PATH := $(call my-dir)
 include $(CLEAR_VARS)
 
@@ -30,9 +26,6 @@
 endif #FLAG_DBG
 
 LOCAL_CFLAGS += -DHOST_TOOL -fPIC -Wno-deprecated -Wno-unused-parameter -Wno-unused-function
-ifneq ($(strip $(HOST_JDK_IS_64BIT_VERSION)),)
-LOCAL_MULTILIB := 64
-endif #HOST_JDK_IS_64BIT_VERSION
 
 LATINIME_NATIVE_JNI_DIR := $(LATINIME_DIR_RELATIVE_TO_DICTTOOL)/native/jni
 LATINIME_NATIVE_SRC_DIR := $(LATINIME_DIR_RELATIVE_TO_DICTTOOL)/native/jni/src
@@ -48,9 +41,6 @@
 
 include $(BUILD_HOST_SHARED_LIBRARY)
 
-endif # Darwin - TODO: Remove this
-
 # Clear our private variables
 include $(LOCAL_PATH)/$(LATINIME_NATIVE_JNI_DIR)/CleanupNativeFileList.mk
 LATINIME_DIR_RELATIVE_TO_DICTTOOL := ../..
-LATINIME_HOST_OSNAME :=