diff --git a/mkfs/mkfs.c b/mkfs/mkfs.c
index 6f4bd9b..f39983d 100644
--- a/mkfs/mkfs.c
+++ b/mkfs/mkfs.c
@@ -20,7 +20,7 @@
 // Disk layout:
 // [ boot block | sb block | log | inode blocks | free bit map | data blocks ]
 
-int nbitmap = FSSIZE/(BSIZE*8) + 1;
+int nbitmap = FSSIZE/BPB + 1;
 int ninodeblocks = NINODES / IPB + 1;
 int nlog = LOGSIZE;
 int nmeta;    // Number of meta blocks (boot, sb, nlog, inode, bitmap)
@@ -240,7 +240,7 @@ balloc(int used)
   int i;
 
   printf("balloc: first %d blocks have been allocated\n", used);
-  assert(used < BSIZE*8);
+  assert(used < BPB);
   bzero(buf, BSIZE);
   for(i = 0; i < used; i++){
     buf[i/8] = buf[i/8] | (0x1 << (i%8));