1 files changed, 2 insertions, 0 deletions
diff --git a/vm.c b/vm.c
index 279c1ea8e6..7c4d6fe2c1 100644
--- a/vm.c
+++ b/vm.c
@@ -8,7 +8,9 @@
 
 **********************************************************************/
 
+#ifndef VM_CHECK_MODE
 #define VM_CHECK_MODE 0
+#endif
 
 #include "internal.h"
 #include "ruby/vm.h"