diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -4107,7 +4107,7 @@
 	struct lwp *lp;
 	struct proc *p;
 	vm_offset_t    end;
-	int grow_amount;
+	vm_size_t      grow_amount;
 	int rv = KERN_SUCCESS;
 	int is_procstack;
 	int use_read_lock = 1;