diff --git a/native/jni/Android.mk b/native/jni/Android.mk
index 01b32a9..5384648 100644
--- a/native/jni/Android.mk
+++ b/native/jni/Android.mk
@@ -88,6 +88,7 @@
 
 LOCAL_SDK_VERSION := 14
 LOCAL_NDK_STL_VARIANT := c++_static
+LOCAL_CFLAGS := -Wall -Werror
 LOCAL_LDFLAGS += -ldl
 
 include $(BUILD_SHARED_LIBRARY)
@@ -99,3 +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 6dd615c..baf1cac 100644
--- a/native/jni/HostUnitTests.mk
+++ b/native/jni/HostUnitTests.mk
@@ -29,7 +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_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
diff --git a/native/jni/TargetUnitTests.mk b/native/jni/TargetUnitTests.mk
index b05cd14..32aada0 100644
--- a/native/jni/TargetUnitTests.mk
+++ b/native/jni/TargetUnitTests.mk
@@ -21,7 +21,7 @@
 
 #################### Target library for unit test
 LATIN_IME_SRC_DIR := src
-LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function
+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
@@ -33,7 +33,7 @@
 #################### Target native tests
 include $(CLEAR_VARS)
 LATIN_IME_TEST_SRC_DIR := tests
-LOCAL_CFLAGS += -Wno-unused-parameter -Wno-unused-function
+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));