diff --git a/ChangeLog b/ChangeLog
index 17b79034db..d3c1358828 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,9 @@ Tue Oct  2 08:25:50 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
 	* array.c (rb_ary_combination): RDoc update to clarify.  a patch
 	  from David Flanagan.  [ruby-core:12344]
 
+	* array.c (rb_ary_permutation): small dirty hack by Matz to avoid
+	  arrays on stack.
+
 Tue Oct  2 07:01:05 2007  Koichi Sasada  <ko1@atdot.net>
 
 	* proc.c (proc_dup): proc->block.proc should be self.
diff --git a/array.c b/array.c
index 93a95d96e8..801f2e6c2d 100644
--- a/array.c
+++ b/array.c
@@ -3036,8 +3036,11 @@ rb_ary_permutation(VALUE ary, VALUE num)
     }
     else {             /* this is the general case */
 	ary = rb_ary_dup(ary); /* private defensive copy of ary */
-	long p[n];
-	int used[n];
+	volatile VALUE t0 = rb_str_new(0, n*sizeof(long));
+	long *p = (long*)RSTRING_PTR(t0); /* array indexes of current permutation */
+	volatile VALUE t1 = rb_str_new(0, n*sizeof(int));
+	int *used = (int*)RSTRING_PTR(t1); /* booleans: which indexes are already used */
+
 	for(i = 0; i < n; i++) used[i] = 0; /* initialize array */
 
 	permute0(n,r,p,0,used,ary);  /* compute and yield permutations */