diff --git a/ChangeLog b/ChangeLog
index 178a0cfb0d..d74226b069 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Feb 14 18:38:46 2014  Eric Wong  <e@80x24.org>
+
+	* string.c (rb_str_format_m): trade volatile for RB_GC_GUARD
+	  RB_GC_GUARD meaning is clear and has better code generation.
+	  [ruby-core:60688]
+
 Thu Feb 13 23:30:30 2014  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* vm_insnhelper.c (vm_call_method): should check ci->me->flag of
diff --git a/string.c b/string.c
index 589c80088e..4e30cb338a 100644
--- a/string.c
+++ b/string.c
@@ -1401,10 +1401,12 @@ rb_str_times(VALUE str, VALUE times)
 static VALUE
 rb_str_format_m(VALUE str, VALUE arg)
 {
-    volatile VALUE tmp = rb_check_array_type(arg);
+    VALUE tmp = rb_check_array_type(arg);
 
     if (!NIL_P(tmp)) {
-	return rb_str_format(RARRAY_LENINT(tmp), RARRAY_CONST_PTR(tmp), str);
+	VALUE rv = rb_str_format(RARRAY_LENINT(tmp), RARRAY_CONST_PTR(tmp), str);
+	RB_GC_GUARD(tmp);
+	return rv;
     }
     return rb_str_format(1, &arg, str);
 }