diff --git a/memory.c b/memory.c
index 0504905..1cb429b 100644
--- a/memory.c
+++ b/memory.c
@@ -16,10 +16,10 @@ unsigned int addr_bits;
 
 int number_of_blocks(unsigned int addr_bits,
                      unsigned int num_block_offset_bits) {
-    if (addr_bits < num_block_offset_bits || num_block_offset_bits < 0 || addr_bits < 0)
+    if (addr_bits < num_block_offset_bits || num_block_offset_bits <= 0 || addr_bits <= 0)
         return FAIL;
 
-    return addr_bits / exp2(num_block_offset_bits);
+    return exp2(addr_bits - num_block_offset_bits);
 
 }