diff --git a/sys/kern/subr_pool.c b/sys/kern/subr_pool.c
index a34c06ca047f..f536512374cf 100644
--- a/sys/kern/subr_pool.c
+++ b/sys/kern/subr_pool.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: subr_pool.c,v 1.115 2006/04/15 04:47:11 christos Exp $	*/
+/*	$NetBSD: subr_pool.c,v 1.116 2006/04/15 14:23:11 simonb Exp $	*/
 
 /*-
  * Copyright (c) 1997, 1999, 2000 The NetBSD Foundation, Inc.
@@ -38,7 +38,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_pool.c,v 1.115 2006/04/15 04:47:11 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_pool.c,v 1.116 2006/04/15 14:23:11 simonb Exp $");
 
 #include "opt_pool.h"
 #include "opt_poollog.h"
@@ -468,13 +468,27 @@ void
 pool_init(struct pool *pp, size_t size, u_int align, u_int ioff, int flags,
     const char *wchan, struct pool_allocator *palloc)
 {
-	int off, slack;
+#ifdef DEBUG
+	struct pool *pp1;
+#endif
 	size_t trysize, phsize;
-	int s;
+	int off, slack, s;
 
 	KASSERT((1UL << (CHAR_BIT * sizeof(pool_item_freelist_t))) - 2 >=
 	    PHPOOL_FREELIST_NELEM(PHPOOL_MAX - 1));
 
+#ifdef DEBUG
+	/*
+	 * Check that the pool hasn't already been initialised and
+	 * added to the list of all pools.
+	 */
+	LIST_FOREACH(pp1, &pool_head, pr_poollist) {
+		if (pp == pp1)
+			panic("pool_init: pool %s already initialised",
+			    wchan);
+	}
+#endif
+
 #ifdef POOL_DIAGNOSTIC
 	/*
 	 * Always log if POOL_DIAGNOSTIC is defined.