diff --git a/libs/diskusage/Android.bp b/libs/diskusage/Android.bp
index 156ddff..a826306 100644
--- a/libs/diskusage/Android.bp
+++ b/libs/diskusage/Android.bp
@@ -15,4 +15,5 @@
 cc_library_static {
     name: "libdiskusage",
     srcs: ["dirsize.c"],
+    cflags: ["-Wall", "-Werror"],
 }
diff --git a/libs/graphicsenv/Android.bp b/libs/graphicsenv/Android.bp
index f2686d5..9f99538 100644
--- a/libs/graphicsenv/Android.bp
+++ b/libs/graphicsenv/Android.bp
@@ -19,6 +19,8 @@
         "GraphicsEnv.cpp",
     ],
 
+    cflags: ["-Wall", "-Werror"],
+
     shared_libs: [
         "libnativeloader",
         "liblog",
diff --git a/libs/hwc2on1adapter/Android.bp b/libs/hwc2on1adapter/Android.bp
index ec9cbf8..420a1f6 100644
--- a/libs/hwc2on1adapter/Android.bp
+++ b/libs/hwc2on1adapter/Android.bp
@@ -17,9 +17,13 @@
     vendor: true,
 
     clang: true,
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-user-defined-warnings",
+    ],
     cppflags: [
         "-Weverything",
-        "-Wall",
         "-Wunused",
         "-Wunreachable-code",
 
diff --git a/libs/input/tests/Android.bp b/libs/input/tests/Android.bp
index 029a420..0028655 100644
--- a/libs/input/tests/Android.bp
+++ b/libs/input/tests/Android.bp
@@ -7,6 +7,12 @@
         "InputEvent_test.cpp",
         "InputPublisherAndConsumer_test.cpp",
     ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-error=sign-compare", // to fix later
+        "-Wno-unused-variable",
+    ],
     shared_libs: [
         "libinput",
         "libcutils",
@@ -24,5 +30,7 @@
     srcs: ["StructLayout_test.cpp"],
     cflags: [
         "-O0",
+        "-Wall",
+        "-Werror",
     ],
 }
diff --git a/libs/math/tests/Android.bp b/libs/math/tests/Android.bp
index 0ed24a2..0184f56 100644
--- a/libs/math/tests/Android.bp
+++ b/libs/math/tests/Android.bp
@@ -18,22 +18,26 @@
     name: "vec_test",
     srcs: ["vec_test.cpp"],
     static_libs: ["libmath"],
+    cflags: ["-Wall", "-Werror"],
 }
 
 cc_test {
     name: "mat_test",
     srcs: ["mat_test.cpp"],
     static_libs: ["libmath"],
+    cflags: ["-Wall", "-Werror"],
 }
 
 cc_test {
     name: "half_test",
     srcs: ["half_test.cpp"],
     static_libs: ["libmath"],
+    cflags: ["-Wall", "-Werror"],
 }
 
 cc_test {
     name: "quat_test",
     srcs: ["quat_test.cpp"],
     static_libs: ["libmath"],
+    cflags: ["-Wall", "-Werror"],
 }