diff --git a/ChangeLog b/ChangeLog
index 4d3486232d..b515d02a7c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Jun 20 00:05:07 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* gc.c (RVALUE_PROMOTED): fix type.
+
 Wed Jun 19 23:39:01 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* gc.c (garbage_collect_test): rewrite checking code.
diff --git a/gc.c b/gc.c
index 244b40b17e..4e725ac28f 100644
--- a/gc.c
+++ b/gc.c
@@ -526,7 +526,7 @@ RVALUE_PROMOTED(VALUE obj)
     int result = FL_TEST2((obj), FL_OLDGEN);
 
     if (RGENGC_CHECK_MODE > 0) {
-	int bitmap_result = RVALUE_PROMOTED_FROM_BITMAP(obj);
+	int bitmap_result = RVALUE_PROMOTED_FROM_BITMAP(obj) ? TRUE : FALSE;
 	if (!result != !bitmap_result) rb_bug("RVALUE_PROMOTED: %p (%s) flag %d but bitmap is %d\n",
 					      (void *)obj, obj_type_name(obj), !!result, !!bitmap_result);
     }