diff --git a/pb.h b/pb.h
index 63d313d..aca96ee 100644
--- a/pb.h
+++ b/pb.h
@@ -500,7 +500,11 @@ struct _pb_extension_t {
  * messages if not used.
  */
 #ifdef PB_NO_ERRMSG
-#define PB_RETURN_ERROR(stream,msg) return false
+#define PB_RETURN_ERROR(stream,msg) \
+    do {\
+        UNUSED(stream); \
+        return false; \
+    } while(0)
 #define PB_GET_ERROR(stream) "(errmsg disabled)"
 #else
 #define PB_RETURN_ERROR(stream,msg) \