diff --git a/mm/slab.c b/mm/slab.c
index ae6cca0..59d382f 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -189,6 +189,7 @@
  * is less than 512 (PAGE_SIZE<<3), but greater than 256.
  */
 
+typedef unsigned int kmem_bufctl_t;
 #define BUFCTL_END	(((kmem_bufctl_t)(~0U))-0)
 #define BUFCTL_FREE	(((kmem_bufctl_t)(~0U))-1)
 #define	SLAB_LIMIT	(((kmem_bufctl_t)(~0U))-2)