diff --git a/kernel/defs.h b/kernel/defs.h
index fb2672e..2d8f85b 100644
--- a/kernel/defs.h
+++ b/kernel/defs.h
@@ -193,7 +193,7 @@ uint64          walkaddr(pagetable_t, uint64);
 int             copyout(pagetable_t, uint64, char *, uint64);
 int             copyin(pagetable_t, char *, uint64, uint64);
 int             copyinstr(pagetable_t, char *, uint64, uint64);
-char*           map_kstack();
+char*           mapkstack(uint64);
 uint64          kernelpa(uint64);
 void            clearpteu(pagetable_t, uint64);
 
diff --git a/kernel/proc.c b/kernel/proc.c
index d10c952..81c0e98 100644
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -29,8 +29,8 @@ procinit(void)
   for(p = proc; p < &proc[NPROC]; p++) {
       initlock(&p->lock, "proc");
       // Allocate a page for the kernel stack.
-      char *kstack = (char *) KSTACK((int) (p - proc));
-      if((p->kstack = map_kstack(kstack)) == 0) {
+      uint64 kstack = KSTACK((int) (p - proc));
+      if((p->kstack = mapkstack(kstack)) == 0) {
         panic("procinit");
       }
   }
diff --git a/kernel/vm.c b/kernel/vm.c
index cbea684..7dc84ba 100644
--- a/kernel/vm.c
+++ b/kernel/vm.c
@@ -406,13 +406,13 @@ copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max)
 }
 
 char *
-map_kstack(uint64 kstack)
+mapkstack(uint64 kstack)
 {
   char *k = kalloc();
   if(k == 0) {
     return 0;
   }
-  if (mappages(kernel_pagetable, (uint64) kstack, PGSIZE,
+  if (mappages(kernel_pagetable, kstack, PGSIZE,
                (uint64) k, PTE_R | PTE_W) == 0) {
     kvminithart();
     return (char *) kstack;