diff --git a/libcutils/tests/Android.bp b/libcutils/tests/Android.bp
index 0b0dc0910..718d76b49 100644
--- a/libcutils/tests/Android.bp
+++ b/libcutils/tests/Android.bp
@@ -46,6 +46,12 @@ cc_defaults {
             suffix: "64",
         },
     },
+
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Werror",
+    ],
 }
 
 test_libraries = [
diff --git a/libcutils/tests/multiuser_test.cpp b/libcutils/tests/multiuser_test.cpp
index c5f58b450..ae5c4169c 100644
--- a/libcutils/tests/multiuser_test.cpp
+++ b/libcutils/tests/multiuser_test.cpp
@@ -17,59 +17,61 @@
 #include <cutils/multiuser.h>
 #include <gtest/gtest.h>
 
+static constexpr auto ERR_GID = static_cast<gid_t>(-1);
+
 TEST(MultiuserTest, TestMerge) {
-    EXPECT_EQ(0, multiuser_get_uid(0, 0));
-    EXPECT_EQ(1000, multiuser_get_uid(0, 1000));
-    EXPECT_EQ(10000, multiuser_get_uid(0, 10000));
-    EXPECT_EQ(50000, multiuser_get_uid(0, 50000));
-    EXPECT_EQ(1000000, multiuser_get_uid(10, 0));
-    EXPECT_EQ(1001000, multiuser_get_uid(10, 1000));
-    EXPECT_EQ(1010000, multiuser_get_uid(10, 10000));
-    EXPECT_EQ(1050000, multiuser_get_uid(10, 50000));
+    EXPECT_EQ(0U, multiuser_get_uid(0, 0));
+    EXPECT_EQ(1000U, multiuser_get_uid(0, 1000));
+    EXPECT_EQ(10000U, multiuser_get_uid(0, 10000));
+    EXPECT_EQ(50000U, multiuser_get_uid(0, 50000));
+    EXPECT_EQ(1000000U, multiuser_get_uid(10, 0));
+    EXPECT_EQ(1001000U, multiuser_get_uid(10, 1000));
+    EXPECT_EQ(1010000U, multiuser_get_uid(10, 10000));
+    EXPECT_EQ(1050000U, multiuser_get_uid(10, 50000));
 }
 
 TEST(MultiuserTest, TestSplitUser) {
-    EXPECT_EQ(0, multiuser_get_user_id(0));
-    EXPECT_EQ(0, multiuser_get_user_id(1000));
-    EXPECT_EQ(0, multiuser_get_user_id(10000));
-    EXPECT_EQ(0, multiuser_get_user_id(50000));
-    EXPECT_EQ(10, multiuser_get_user_id(1000000));
-    EXPECT_EQ(10, multiuser_get_user_id(1001000));
-    EXPECT_EQ(10, multiuser_get_user_id(1010000));
-    EXPECT_EQ(10, multiuser_get_user_id(1050000));
+    EXPECT_EQ(0U, multiuser_get_user_id(0));
+    EXPECT_EQ(0U, multiuser_get_user_id(1000));
+    EXPECT_EQ(0U, multiuser_get_user_id(10000));
+    EXPECT_EQ(0U, multiuser_get_user_id(50000));
+    EXPECT_EQ(10U, multiuser_get_user_id(1000000));
+    EXPECT_EQ(10U, multiuser_get_user_id(1001000));
+    EXPECT_EQ(10U, multiuser_get_user_id(1010000));
+    EXPECT_EQ(10U, multiuser_get_user_id(1050000));
 }
 
 TEST(MultiuserTest, TestSplitApp) {
-    EXPECT_EQ(0, multiuser_get_app_id(0));
-    EXPECT_EQ(1000, multiuser_get_app_id(1000));
-    EXPECT_EQ(10000, multiuser_get_app_id(10000));
-    EXPECT_EQ(50000, multiuser_get_app_id(50000));
-    EXPECT_EQ(0, multiuser_get_app_id(1000000));
-    EXPECT_EQ(1000, multiuser_get_app_id(1001000));
-    EXPECT_EQ(10000, multiuser_get_app_id(1010000));
-    EXPECT_EQ(50000, multiuser_get_app_id(1050000));
+    EXPECT_EQ(0U, multiuser_get_app_id(0));
+    EXPECT_EQ(1000U, multiuser_get_app_id(1000));
+    EXPECT_EQ(10000U, multiuser_get_app_id(10000));
+    EXPECT_EQ(50000U, multiuser_get_app_id(50000));
+    EXPECT_EQ(0U, multiuser_get_app_id(1000000));
+    EXPECT_EQ(1000U, multiuser_get_app_id(1001000));
+    EXPECT_EQ(10000U, multiuser_get_app_id(1010000));
+    EXPECT_EQ(50000U, multiuser_get_app_id(1050000));
 }
 
 TEST(MultiuserTest, TestCache) {
-    EXPECT_EQ(-1, multiuser_get_cache_gid(0, 0));
-    EXPECT_EQ(-1, multiuser_get_cache_gid(0, 1000));
-    EXPECT_EQ(20000, multiuser_get_cache_gid(0, 10000));
-    EXPECT_EQ(-1, multiuser_get_cache_gid(0, 50000));
-    EXPECT_EQ(1020000, multiuser_get_cache_gid(10, 10000));
+    EXPECT_EQ(ERR_GID, multiuser_get_cache_gid(0, 0));
+    EXPECT_EQ(ERR_GID, multiuser_get_cache_gid(0, 1000));
+    EXPECT_EQ(20000U, multiuser_get_cache_gid(0, 10000));
+    EXPECT_EQ(ERR_GID, multiuser_get_cache_gid(0, 50000));
+    EXPECT_EQ(1020000U, multiuser_get_cache_gid(10, 10000));
 }
 
 TEST(MultiuserTest, TestExt) {
-    EXPECT_EQ(-1, multiuser_get_ext_gid(0, 0));
-    EXPECT_EQ(-1, multiuser_get_ext_gid(0, 1000));
-    EXPECT_EQ(30000, multiuser_get_ext_gid(0, 10000));
-    EXPECT_EQ(-1, multiuser_get_ext_gid(0, 50000));
-    EXPECT_EQ(1030000, multiuser_get_ext_gid(10, 10000));
+    EXPECT_EQ(ERR_GID, multiuser_get_ext_gid(0, 0));
+    EXPECT_EQ(ERR_GID, multiuser_get_ext_gid(0, 1000));
+    EXPECT_EQ(30000U, multiuser_get_ext_gid(0, 10000));
+    EXPECT_EQ(ERR_GID, multiuser_get_ext_gid(0, 50000));
+    EXPECT_EQ(1030000U, multiuser_get_ext_gid(10, 10000));
 }
 
 TEST(MultiuserTest, TestShared) {
-    EXPECT_EQ(-1, multiuser_get_shared_gid(0, 0));
-    EXPECT_EQ(-1, multiuser_get_shared_gid(0, 1000));
-    EXPECT_EQ(50000, multiuser_get_shared_gid(0, 10000));
-    EXPECT_EQ(-1, multiuser_get_shared_gid(0, 50000));
-    EXPECT_EQ(1050000, multiuser_get_shared_gid(10, 10000));
+    EXPECT_EQ(ERR_GID, multiuser_get_shared_gid(0, 0));
+    EXPECT_EQ(ERR_GID, multiuser_get_shared_gid(0, 1000));
+    EXPECT_EQ(50000U, multiuser_get_shared_gid(0, 10000));
+    EXPECT_EQ(ERR_GID, multiuser_get_shared_gid(0, 50000));
+    EXPECT_EQ(1050000U, multiuser_get_shared_gid(10, 10000));
 }
diff --git a/libcutils/tests/sockets_test.cpp b/libcutils/tests/sockets_test.cpp
index 0441fb636..b762ac15e 100644
--- a/libcutils/tests/sockets_test.cpp
+++ b/libcutils/tests/sockets_test.cpp
@@ -101,7 +101,7 @@ TEST(SocketsTest, TestGetLocalPort) {
     // should always be able to read its port.
     for (int port : {10000, 12345, 15999, 20202, 25000}) {
         for (int type : {SOCK_DGRAM, SOCK_STREAM}) {
-            server = socket_inaddr_any_server(port, SOCK_DGRAM);
+            server = socket_inaddr_any_server(port, type);
             if (server != INVALID_SOCKET) {
                 EXPECT_EQ(port, socket_get_local_port(server));
             }