diff --git a/ChangeLog b/ChangeLog
index fc08a9ebbd..2ec5224307 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Jul  7 14:40:08 2015  Koichi Sasada  <ko1@atdot.net>
+
+	* vm_backtrace.c: remove debug flag introduced accidentaly.
+
 Tue Jul  7 12:05:37 2015  Koichi Sasada  <ko1@atdot.net>
 
 	* cont.c (cont_free): remove mysterious fflush()
diff --git a/vm_backtrace.c b/vm_backtrace.c
index 3d4322cd4d..aabc949f64 100644
--- a/vm_backtrace.c
+++ b/vm_backtrace.c
@@ -9,8 +9,6 @@
 
 **********************************************************************/
 
-#define VM_CHECK_MODE 2
-
 #include "internal.h"
 #include "ruby/debug.h"