diff --git a/include/input/Flags.h b/include/input/Flags.h
index 072dd18..b12a9ed 100644
--- a/include/input/Flags.h
+++ b/include/input/Flags.h
@@ -84,7 +84,7 @@
 template <typename F>
 constexpr std::optional<std::string_view> flag_name(F flag) {
     using U = std::underlying_type_t<F>;
-    auto idx = __builtin_ctzl(static_cast<U>(flag));
+    auto idx = static_cast<size_t>(__builtin_ctzl(static_cast<U>(flag)));
     return details::flag_names<F>[idx];
 }
 
@@ -280,4 +280,4 @@
 } // namespace flag_operators
 } // namespace android
 
-#endif // __UI_INPUT_FLAGS_H
\ No newline at end of file
+#endif // __UI_INPUT_FLAGS_H