diff --git a/vm_exec.h b/vm_exec.h
index f06399033d..26cd762a26 100644
--- a/vm_exec.h
+++ b/vm_exec.h
@@ -17,7 +17,7 @@ typedef unsigned long lindex_t;
 typedef VALUE GENTRY;
 typedef rb_iseq_t *ISEQ;
 
-#ifdef __GCC__
+#ifdef __GNUC__
 /* TODO: machine dependent prefetch instruction */
 #define PREFETCH(pc)
 #else