diff --git a/ChangeLog b/ChangeLog
index 49ec403c42..c4001532d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Nov 21 14:55:13 2007  Koichi Sasada  <ko1@atdot.net>
+
+	* array.c (rb_ary_permutation): add gc guard codes.
+
 Wed Nov 21 03:12:50 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* process.c (rb_f_system): returns nil on execution failure.
diff --git a/array.c b/array.c
index 403d8b3c5a..b0010672c4 100644
--- a/array.c
+++ b/array.c
@@ -3047,15 +3047,17 @@ rb_ary_permutation(int argc, VALUE *argv, VALUE ary)
 	}
     }
     else {             /* this is the general case */
-	volatile VALUE t0 = tmpbuf(n,sizeof(long));
+	VALUE t0 = tmpbuf(n,sizeof(long));
 	long *p = (long*)RSTRING_PTR(t0);
-	volatile VALUE t1 = tmpbuf(n,sizeof(int));
+	VALUE t1 = tmpbuf(n,sizeof(int));
 	int *used = (int*)RSTRING_PTR(t1);
 	VALUE ary0 = ary_make_shared(ary); /* private defensive copy of ary */
 
 	for (i = 0; i < n; i++) used[i] = 0; /* initialize array */
 
 	permute0(n, r, p, 0, used, ary0); /* compute and yield permutations */
+	RB_GC_GUARD(t0);
+	RB_GC_GUARD(t1);
     }
     return ary;
 }