diff --git a/kernel/vm.c b/kernel/vm.c
index d42e719..f7ca101 100644
--- a/kernel/vm.c
+++ b/kernel/vm.c
@@ -405,7 +405,8 @@ copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max)
   }
 }
 
-char *map_kstack(uint64 kstack)
+char
+*map_kstack(uint64 kstack)
 {
   char *k = kalloc();
   if(k == 0) {