diff --git a/mmu.h b/mmu.h
index 544de31..fdc9924 100644
--- a/mmu.h
+++ b/mmu.h
@@ -95,7 +95,6 @@ struct segdesc {
 #define NPDENTRIES      512    // # directory entries per page directory
 #define PGSIZE          4096    // bytes mapped by a page
 #define PGSHIFT         12      // offset of PTX in a linear address
-#define PDXSHIFT        21      // offset of PDX in a linear address
 
 #define PXMASK          0x1FF
 #define PXSHIFT(n)	(PGSHIFT+(9*(n)))
@@ -103,9 +102,6 @@ struct segdesc {
 #define PX(n, va)	((((uint64) (va)) >> PXSHIFT(n)) & PXMASK)
 #define L_PML4           3
     
-// construct virtual address from indexes and offset
-#define PGADDR(d, t, o) ((uint64)((d) << PDXSHIFT | (t) << PGSHIFT | (o)))
-
 #define PGROUNDUP(sz)  (((sz)+PGSIZE-1) & ~(PGSIZE-1))
 #define PGROUNDDOWN(a) (((a)) & ~(PGSIZE-1))
 
diff --git a/vm.c b/vm.c
index 9279748..444ec6d 100644
--- a/vm.c
+++ b/vm.c
@@ -305,7 +305,7 @@ deallocuvm(pde_t *pml4, uint64 oldsz, uint64 newsz)
   for(; a  < oldsz; a += PGSIZE){
     pte = walkpgdir(pml4, (char*)a, 0);
     if(!pte)
-      a = PGADDR(PDX(a) + 1, 0, 0) - PGSIZE;
+      continue;
     else if((*pte & PTE_P) != 0){
       pa = PTE_ADDR(*pte);
       if(pa == 0)
@@ -327,7 +327,7 @@ freelevel(pde_t *pgtab, int level) {
   if (level > 0) {
     for(i = 0; i < NPDENTRIES; i++) {
       if(pgtab[i] & PTE_P){
-        pd = (pdpe_t*)P2V(PTE_ADDR(pgtab[i]));
+        pd = (pde_t*)P2V(PTE_ADDR(pgtab[i]));
         freelevel(pd, level-1);
       }
     }