diff --git a/libsrc/c128/mcbdefault.s b/libsrc/c128/mcbdefault.s
index eb521eb3a..a3ca3d0d1 100644
--- a/libsrc/c128/mcbdefault.s
+++ b/libsrc/c128/mcbdefault.s
@@ -19,12 +19,12 @@
 
 ; Sprite definitions. The first value can be changed to adjust the number
 ; of the sprite used for the mouse. All others depend on this value.
-MOUSE_SPR       = 0                             ; Sprite used for the mouse
-MOUSE_SPR_MEM   = $0E00                         ; Memory location
-MOUSE_SPR_MASK  = $01 .shl MOUSE_SPR            ; Positive mask
-MOUSE_SPR_NMASK = .lobyte(.not MOUSE_SPR_MASK)  ; Negative mask
-VIC_SPR_X       = (VIC_SPR0_X + 2*MOUSE_SPR)    ; Sprite X register
-VIC_SPR_Y       = (VIC_SPR0_Y + 2*MOUSE_SPR)    ; Sprite Y register
+MOUSE_SPR       = 0                                     ; Sprite used for the mouse
+MOUSE_SPR_MEM   = $0E00                                 ; Memory location
+MOUSE_SPR_MASK  = $01 .shl MOUSE_SPR                    ; Positive mask
+MOUSE_SPR_NMASK = .lobyte(.bitnot MOUSE_SPR_MASK)       ; Negative mask
+VIC_SPR_X       = (VIC_SPR0_X + 2*MOUSE_SPR)            ; Sprite X register
+VIC_SPR_Y       = (VIC_SPR0_Y + 2*MOUSE_SPR)            ; Sprite Y register
 
 ; --------------------------------------------------------------------------
 ; Initialize the mouse sprite.
diff --git a/libsrc/c64/mcbdefault.s b/libsrc/c64/mcbdefault.s
index dd2f7cee7..79a8d93e5 100644
--- a/libsrc/c64/mcbdefault.s
+++ b/libsrc/c64/mcbdefault.s
@@ -21,11 +21,11 @@
 
 ; Sprite definitions. The first value can be changed to adjust the number
 ; of the sprite used for the mouse. All others depend on this value.
-MOUSE_SPR       = 0                             ; Sprite used for the mouse
-MOUSE_SPR_MASK  = $01 .shl MOUSE_SPR            ; Positive mask
-MOUSE_SPR_NMASK = .lobyte(.not MOUSE_SPR_MASK)  ; Negative mask
-VIC_SPR_X       = (VIC_SPR0_X + 2*MOUSE_SPR)    ; Sprite X register
-VIC_SPR_Y       = (VIC_SPR0_Y + 2*MOUSE_SPR)    ; Sprite Y register
+MOUSE_SPR       = 0                                     ; Sprite used for the mouse
+MOUSE_SPR_MASK  = $01 .shl MOUSE_SPR                    ; Positive mask
+MOUSE_SPR_NMASK = .lobyte(.bitnot MOUSE_SPR_MASK)       ; Negative mask
+VIC_SPR_X       = (VIC_SPR0_X + 2*MOUSE_SPR)            ; Sprite X register
+VIC_SPR_Y       = (VIC_SPR0_Y + 2*MOUSE_SPR)            ; Sprite Y register
 
 ; --------------------------------------------------------------------------
 ; Initialize the mouse sprite.
diff --git a/libsrc/cbm510/mcbdefault.s b/libsrc/cbm510/mcbdefault.s
index 700dcebb1..53eb804c0 100644
--- a/libsrc/cbm510/mcbdefault.s
+++ b/libsrc/cbm510/mcbdefault.s
@@ -21,12 +21,12 @@
 
 ; Sprite definitions. The first value can be changed to adjust the number
 ; of the sprite used for the mouse. All others depend on that value.
-MOUSE_SPR       = 0                             ; Sprite used for the mouse
-MOUSE_SPR_MEM   = $F400                         ; Memory location
-MOUSE_SPR_MASK  = $01 .shl MOUSE_SPR            ; Positive mask
-MOUSE_SPR_NMASK = .lobyte(.not MOUSE_SPR_MASK)  ; Negative mask
-VIC_SPR_X       = (VIC_SPR0_X + 2*MOUSE_SPR)    ; Sprite X register
-VIC_SPR_Y       = (VIC_SPR0_Y + 2*MOUSE_SPR)    ; Sprite Y register
+MOUSE_SPR       = 0                                     ; Sprite used for the mouse
+MOUSE_SPR_MEM   = $F400                                 ; Memory location
+MOUSE_SPR_MASK  = $01 .shl MOUSE_SPR                    ; Positive mask
+MOUSE_SPR_NMASK = .lobyte(.bitnot MOUSE_SPR_MASK)       ; Negative mask
+VIC_SPR_X       = (VIC_SPR0_X + 2*MOUSE_SPR)            ; Sprite X register
+VIC_SPR_Y       = (VIC_SPR0_Y + 2*MOUSE_SPR)            ; Sprite Y register
 
 ; --------------------------------------------------------------------------
 ; Initialize the mouse sprite.