diff --git a/Android.bp b/Android.bp
index 7ae27e8..d8a4f6a 100644
--- a/Android.bp
+++ b/Android.bp
@@ -29,7 +29,11 @@
         "libdl",
         "libvndksupport",
     ],
-    cflags: ["-DQEMU_HARDWARE"],
+    cflags: [
+        "-DQEMU_HARDWARE",
+        "-Wall",
+        "-Werror",
+    ],
 
     header_libs: ["libhardware_headers"],
     export_header_lib_headers: ["libhardware_headers"],
diff --git a/modules/consumerir/Android.bp b/modules/consumerir/Android.bp
index 6ba37b6..4f700c2 100644
--- a/modules/consumerir/Android.bp
+++ b/modules/consumerir/Android.bp
@@ -17,6 +17,7 @@
     relative_install_path: "hw",
     proprietary: true,
     srcs: ["consumerir.c"],
+    cflags: ["-Wall", "-Werror"],
     header_libs: ["libhardware_headers"],
     shared_libs: [
         "liblog",
diff --git a/modules/fingerprint/Android.bp b/modules/fingerprint/Android.bp
index a824608..22648b1 100644
--- a/modules/fingerprint/Android.bp
+++ b/modules/fingerprint/Android.bp
@@ -17,6 +17,7 @@
     relative_install_path: "hw",
     proprietary: true,
     srcs: ["fingerprint.c"],
+    cflags: ["-Wall", "-Werror"],
     header_libs: ["libhardware_headers"],
     shared_libs: ["liblog"],
 }
diff --git a/modules/local_time/Android.bp b/modules/local_time/Android.bp
index 153b7e4..9f140b3 100644
--- a/modules/local_time/Android.bp
+++ b/modules/local_time/Android.bp
@@ -26,6 +26,7 @@
     relative_install_path: "hw",
     proprietary: true,
     srcs: ["local_time_hw.c"],
+    cflags: ["-Wall", "-Werror"],
     header_libs: ["libhardware_headers"],
     shared_libs: [
         "liblog",
diff --git a/modules/local_time/local_time_hw.c b/modules/local_time/local_time_hw.c
index a2d1a9e..0350e24 100644
--- a/modules/local_time/local_time_hw.c
+++ b/modules/local_time/local_time_hw.c
@@ -72,8 +72,6 @@
                      hw_device_t** device)
 {
     struct stub_local_time_device *ltdev;
-    struct timespec ts;
-    int ret;
 
     if (strcmp(name, LOCAL_TIME_HARDWARE_INTERFACE) != 0)
         return -EINVAL;
diff --git a/modules/nfc-nci/Android.bp b/modules/nfc-nci/Android.bp
index f78b7c5..282e925 100644
--- a/modules/nfc-nci/Android.bp
+++ b/modules/nfc-nci/Android.bp
@@ -22,4 +22,5 @@
         "liblog",
         "libcutils",
     ],
+    cflags: ["-Wall", "-Werror"],
 }
diff --git a/modules/nfc/Android.bp b/modules/nfc/Android.bp
index b4bc9b1..7c69f11 100644
--- a/modules/nfc/Android.bp
+++ b/modules/nfc/Android.bp
@@ -17,6 +17,7 @@
     relative_install_path: "hw",
     proprietary: true,
     srcs: ["nfc_pn544_example.c"],
+    cflags: ["-Wall", "-Werror"],
     header_libs: ["libhardware_headers"],
     shared_libs: [
         "liblog",
diff --git a/modules/power/Android.bp b/modules/power/Android.bp
index 41ac45c..6b0b31f 100644
--- a/modules/power/Android.bp
+++ b/modules/power/Android.bp
@@ -17,6 +17,7 @@
     relative_install_path: "hw",
     proprietary: true,
     srcs: ["power.c"],
+    cflags: ["-Wall", "-Werror"],
     header_libs: [
         "libhardware_headers",
         "libutils_headers",
diff --git a/modules/sensors/Android.bp b/modules/sensors/Android.bp
index 1b5f26d..f39ba52 100644
--- a/modules/sensors/Android.bp
+++ b/modules/sensors/Android.bp
@@ -15,4 +15,5 @@
         "libdl"
     ],
     export_include_dirs: ["."],
+    cflags: ["-Wall", "-Werror"],
 }
diff --git a/modules/sensors/multihal.cpp b/modules/sensors/multihal.cpp
index b5360cc..a1f0104 100644
--- a/modules/sensors/multihal.cpp
+++ b/modules/sensors/multihal.cpp
@@ -515,6 +515,7 @@
     if (ctx != NULL) {
         int retval = ctx->close();
         delete ctx;
+        return retval;
     }
 
     if (sub_hw_modules != nullptr) {
@@ -586,15 +587,6 @@
 static int open_sensors(const struct hw_module_t* module, const char* name,
         struct hw_device_t** device);
 
-static bool starts_with(const char* s, const char* prefix) {
-    if (s == NULL || prefix == NULL) {
-        return false;
-    }
-    size_t s_size = strlen(s);
-    size_t prefix_size = strlen(prefix);
-    return s_size >= prefix_size && strncmp(s, prefix, prefix_size) == 0;
-}
-
 /*
  * Adds valid paths from the config file to the vector passed in.
  * The vector must not be null.
diff --git a/modules/tv_input/Android.bp b/modules/tv_input/Android.bp
index 4d2369e..b9d8afa 100644
--- a/modules/tv_input/Android.bp
+++ b/modules/tv_input/Android.bp
@@ -22,4 +22,5 @@
         "liblog",
     ],
     srcs: ["tv_input.cpp"],
+    cflags: ["-Wall", "-Werror"],
 }
diff --git a/modules/vibrator/Android.bp b/modules/vibrator/Android.bp
index fdbfd61..13ffc83 100644
--- a/modules/vibrator/Android.bp
+++ b/modules/vibrator/Android.bp
@@ -21,5 +21,6 @@
     proprietary: true,
     header_libs: ["libhardware_headers"],
     srcs: ["vibrator.c"],
+    cflags: ["-Wall", "-Werror"],
     shared_libs: ["liblog"],
 }
diff --git a/modules/vibrator/vibrator.c b/modules/vibrator/vibrator.c
index 950bc59..8042b57 100644
--- a/modules/vibrator/vibrator.c
+++ b/modules/vibrator/vibrator.c
@@ -108,7 +108,6 @@
 
 static bool vibra_led_exists()
 {
-    int fd;
     char file_str[50];
 
     snprintf(file_str, sizeof(file_str), "%s/%s", LED_DEVICE, "activate");
diff --git a/tests/fingerprint/Android.bp b/tests/fingerprint/Android.bp
index 7de3dee..9524b7b 100644
--- a/tests/fingerprint/Android.bp
+++ b/tests/fingerprint/Android.bp
@@ -9,6 +9,7 @@
 
     cflags: [
         "-Wall",
+        "-Werror",
         "-Wextra",
     ],
 }
diff --git a/tests/nusensors/Android.bp b/tests/nusensors/Android.bp
index e923468..8b267db 100644
--- a/tests/nusensors/Android.bp
+++ b/tests/nusensors/Android.bp
@@ -3,6 +3,8 @@
 
     srcs: ["nusensors.cpp"],
 
+    cflags: ["-Wall", "-Werror"],
+
     shared_libs: [
         "libcutils",
         "libhardware",