diff --git a/fs_mgr/libsnapshot/snapuserd/Android.bp b/fs_mgr/libsnapshot/snapuserd/Android.bp
index 7aac4be..47a8685 100644
--- a/fs_mgr/libsnapshot/snapuserd/Android.bp
+++ b/fs_mgr/libsnapshot/snapuserd/Android.bp
@@ -74,6 +74,11 @@
         "user-space-merge/worker.cpp",
         "utility.cpp",
     ],
+    cflags: [
+        "-D_FILE_OFFSET_BITS=64",
+        "-Wall",
+        "-Werror",
+    ],
     static_libs: [
         "libbase",
         "libdm",
@@ -106,6 +111,8 @@
 
     cflags: [
         "-D_FILE_OFFSET_BITS=64",
+        "-Wall",
+        "-Werror",
     ],
 
     static_libs: [
@@ -230,6 +237,11 @@
         "testing/host_harness.cpp",
         "user-space-merge/snapuserd_test.cpp",
     ],
+    cflags: [
+        "-D_FILE_OFFSET_BITS=64",
+        "-Wall",
+        "-Werror",
+    ],
     shared_libs: [
         "libbase",
         "liblog",
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.h b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.h
index 622fc50..e401c11 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.h
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.h
@@ -249,6 +249,7 @@
 };
 
 std::ostream& operator<<(std::ostream& os, MERGE_IO_TRANSITION value);
+static_assert(sizeof(off_t) == sizeof(uint64_t));
 
 }  // namespace snapshot
 }  // namespace android