diff --git a/src/hb-object-private.h b/src/hb-object-private.h
index 27f1471bc..b371d732a 100644
--- a/src/hb-object-private.h
+++ b/src/hb-object-private.h
@@ -42,7 +42,7 @@
 					  HB_REFERENCE_COUNT_GET_VALUE (obj->ref_count), \
 					  __FUNCTION__)
 #else
-#define HB_OBJECT_DEBUG_OUT(obj) 0
+#define HB_OBJECT_DEBUG_OUT(obj) (void) 0
 #endif