diff --git a/ChangeLog b/ChangeLog
index c877140053..42ee98d735 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Jul 17 18:11:32 2009  Tanaka Akira  <akr@fsij.org>
+
+	* struct.c (recursive_hash): extracted from rb_struct_hash.  reject
+	  recursive key.
+	  (rb_struct_hash): use recursive_hash.
+
 Fri Jul 17 16:45:22 2009  Tanaka Akira  <akr@fsij.org>
 
 	* array.c (recursive_hash): reject recursive key.
diff --git a/struct.c b/struct.c
index a93ed65f7d..e4b6da0e76 100644
--- a/struct.c
+++ b/struct.c
@@ -802,6 +802,25 @@ rb_struct_equal(VALUE s, VALUE s2)
     return Qtrue;
 }
 
+static VALUE
+recursive_hash(VALUE s, VALUE dummy, int recur)
+{
+    long i;
+    unsigned long h;
+    VALUE n;
+
+    if (recur) {
+        rb_raise(rb_eArgError, "recursive key for hash");
+    }
+    h = rb_hash_start(rb_hash(rb_obj_class(s)));
+    for (i = 0; i < RSTRUCT_LEN(s); i++) {
+	n = rb_hash(RSTRUCT_PTR(s)[i]);
+	h = rb_hash_uint(h, NUM2LONG(n));
+    }
+    h = rb_hash_end(h);
+    return INT2FIX(h);
+}
+
 /*
  * call-seq:
  *   struct.hash   => fixnum
@@ -812,17 +831,7 @@ rb_struct_equal(VALUE s, VALUE s2)
 static VALUE
 rb_struct_hash(VALUE s)
 {
-    long i;
-    unsigned long h;
-    VALUE n;
-
-    h = rb_hash_start(rb_hash(rb_obj_class(s)));
-    for (i = 0; i < RSTRUCT_LEN(s); i++) {
-	n = rb_hash(RSTRUCT_PTR(s)[i]);
-	h = rb_hash_uint(h, NUM2LONG(n));
-    }
-    h = rb_hash_end(h);
-    return INT2FIX(h);
+    return rb_exec_recursive(recursive_hash, s, 0);
 }
 
 /*