diff --git a/firmware/FIRMWARE.ZXD b/firmware/FIRMWARE.ZXD
index 127592f..bdc48f0 100644
Binary files a/firmware/FIRMWARE.ZXD and b/firmware/FIRMWARE.ZXD differ
diff --git a/firmware/firmware.asm b/firmware/firmware.asm
index 6ae3389..b028c05 100644
--- a/firmware/firmware.asm
+++ b/firmware/firmware.asm
@@ -3181,10 +3181,10 @@ calbi3    add     hl, de
         ELSE
 calbi1    ld      a, b        ;1-40
           sub     20
+          jr      z, calbi2
           jr      c, calbi2   ;<20 c n
           ld      b, a        ;>=20 nc n-20
 calbi2    ld      hl, $fec0
-          ret     z
           ld      de, $0c40
 calbi3    add     hl, de
           djnz    calbi3