diff --git a/src/kernal/board_m65/mega65_viciv_shutdown.s b/src/kernal/board_m65/mega65_viciv_shutdown.s
index e53b6f0e..0a4492a5 100644
--- a/src/kernal/board_m65/mega65_viciv_shutdown.s
+++ b/src/kernal/board_m65/mega65_viciv_shutdown.s
@@ -23,6 +23,10 @@ viciv_shutdown:
 	sta VIC_CTRLA  ; enable C64 character set
 	sta VIC_CTRLB  ; disable extended resolution and attributes
 
+	lda VIC_CTRLC
+	and #%00101000 ; disable fast mode and various VIC-IV extensions
+	sta VIC_CTRLC
+
 	; Reenable hot registers
 
 	jsr viciv_hotregs_on
diff --git a/src/kernal/init/e5a0.vicii_init.s b/src/kernal/init/e5a0.vicii_init.s
index 1657e714..d4637ce4 100644
--- a/src/kernal/init/e5a0.vicii_init.s
+++ b/src/kernal/init/e5a0.vicii_init.s
@@ -35,11 +35,12 @@ vicii_init:
 
  	; Disable C128 extra keys - just to be sure they will not interfere with anything
 
- 	stx VIC_XSCAN
+ 	stx VIC_XSCAN                      ; store $FF
 
  	; Disable the C128 2MHz mode, it prevents VIC-II display from working correctly
 
- 	stx VIC_CLKRATE
+ 	inx
+	stx VIC_CLKRATE                    ; store $00
 } }
 
 	; Set up default IO values