diff --git a/io.asm b/io.asm
index 1b56611..b2f5f66 100644
--- a/io.asm
+++ b/io.asm
@@ -148,7 +148,7 @@ parameters_320k:
 	dw 512 ; Sector size in bytes
 	db 2 ; Sectors per cluster
 	dw 1 ; Number of reserved sectors
-	dw 2 ; Number of FATs
+	db 2 ; Number of FATs
 	dw 112 ; Number of directory entries
 	dw 320*2 ; Number of sectors