diff --git a/src/port.h b/src/port.h
index 7f451ab3..d2a1db03 100644
--- a/src/port.h
+++ b/src/port.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#if defined(__GNUC__) && !defined(__clang__)
+#if defined(__GNUC__)
 #define ATTRIBUTE_UNUSED __attribute__((unused))
 #else
 #define ATTRIBUTE_UNUSED
diff --git a/src/serializer.h b/src/serializer.h
index 1132af14..2e66737f 100644
--- a/src/serializer.h
+++ b/src/serializer.h
@@ -82,7 +82,7 @@ struct IndexFile;
     ::Reflect(visitor, value0);                                         \
     value = static_cast<type>(value0);                                  \
   }                                                                     \
-  inline void Reflect(Writer& visitor, type& value) {                   \
+  ATTRIBUTE_UNUSED inline void Reflect(Writer& visitor, type& value) {  \
     auto value0 = static_cast<as_type>(value);                          \
     ::Reflect(visitor, value0);                                         \
   }