diff --git a/src/prelaunch/slicks.a b/src/prelaunch/slicks.a
index 89a72b95d..344b9c725 100644
--- a/src/prelaunch/slicks.a
+++ b/src/prelaunch/slicks.a
@@ -19,6 +19,7 @@
 
          +READ_RAM2_NO_WRITE
          lda   MockingboardStuff
+         and   #7
          cmp   #1
          ora   #$C0
          bcc   skipmb
diff --git a/src/prelaunch/zaxxon.a b/src/prelaunch/zaxxon.a
index cdbad604b..204bf4dc1 100644
--- a/src/prelaunch/zaxxon.a
+++ b/src/prelaunch/zaxxon.a
@@ -21,6 +21,7 @@
          jsr   $D15B      ; decompress Mockingboard code
          tax
          pla
+         and   #7
          ora   #$C0
 -        ldy   $70B, x
          cpy   #$C4