diff --git a/kernel/proc.c b/kernel/proc.c
index ef2ad68..0cb5afe 100644
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -176,8 +176,7 @@ proc_freepagetable(pagetable_t pagetable, uint64 sz)
 {
   uvmunmap(pagetable, TRAMPOLINE, PGSIZE, 0);
   uvmunmap(pagetable, TRAPFRAME, PGSIZE, 0);
-  if(sz > 0)
-    uvmfree(pagetable, sz);
+  uvmfree(pagetable, sz);
 }
 
 // a user program that calls exec("/init")
diff --git a/kernel/vm.c b/kernel/vm.c
index c5da0c1..3004bb3 100644
--- a/kernel/vm.c
+++ b/kernel/vm.c
@@ -301,7 +301,8 @@ freewalk(pagetable_t pagetable)
 void
 uvmfree(pagetable_t pagetable, uint64 sz)
 {
-  uvmunmap(pagetable, 0, sz, 1);
+  if(sz > 0)
+    uvmunmap(pagetable, 0, sz, 1);
   freewalk(pagetable);
 }