1 files changed, 2 insertions, 0 deletions
diff --git a/vm.c b/vm.c
index fc58d07c6d..6cfea72e33 100644
--- a/vm.c
+++ b/vm.c
@@ -987,6 +987,7 @@ vm_init_redefined_flag(void)
 
 /* for vm development */
 
+#if VMDEBUG
 static const char *
 vm_frametype_name(const rb_control_frame_t *cfp)
 {
@@ -1005,6 +1006,7 @@ vm_frametype_name(const rb_control_frame_t *cfp)
 	rb_bug("unknown frame");
     }
 }
+#endif
 
 /* evaluator body */