diff --git a/boot0.s b/boot0.s
index a71c5d3..001c056 100644
--- a/boot0.s
+++ b/boot0.s
@@ -104,12 +104,11 @@ main:
   ; - If each entry is smaller than a sector, an integer number of them will fit into a sector.
   or eax, eax  ; Test size != 0 because 128 * 2^n != 0
   jz panic
-  and eax, 127 ; Test size is a multiple of 128
+  test eax, 127 ; Test size is a multiple of 128
   jnz panic
   ; Use the (n & (n - 1)) == 0 trick to test if the entry size is a power of 2. Since we already
   ; know it's a nonzero multiple of 128, if size is a power of 2 then size = 128 * 2^n holds.
   ; Therefore we don't need to bother dividing by 128 first (shr 7), which saves a couple of bytes.
-  mov eax, ebx
   mov ecx, ebx
   dec ecx
   and ecx, eax