diff --git a/kernel/trunk/fs/part_set.inc b/kernel/trunk/fs/part_set.inc
index 458b7a40ec..4d9ed4120f 100644
--- a/kernel/trunk/fs/part_set.inc
+++ b/kernel/trunk/fs/part_set.inc
@@ -388,7 +388,7 @@ boot_read_ok:
     mov   [SECTORS_PER_CLUSTER],eax
 
     movzx ecx,word [ebx+0xb]    ; bytes per sector
-    cmp   eax,0x200
+    cmp   ecx,0x200
     jnz   problem_fat_dec_count
     mov   [BYTES_PER_SECTOR],ecx