diff --git a/libsrc/apple2/curdevice.s b/libsrc/apple2/curdevice.s
index 9781b8ad0..a450c605f 100644
--- a/libsrc/apple2/curdevice.s
+++ b/libsrc/apple2/curdevice.s
@@ -23,5 +23,5 @@ _getcurrentdevice:
         bne     :+
         lda     #$FF            ; INVALID_DEVICE
 
-:       ldx     #$00
+:       ldx     #>$0000
         rts
diff --git a/libsrc/apple2/diocommon.s b/libsrc/apple2/diocommon.s
index b18f0e6ef..6870ebb51 100644
--- a/libsrc/apple2/diocommon.s
+++ b/libsrc/apple2/diocommon.s
@@ -31,5 +31,5 @@ diocommon:
 dioepilog:
         ; Return success or error
         sta     ___oserror
-        ldx     #$00
+        ldx     #>$0000
         rts
diff --git a/libsrc/apple2/get_iigs_speed.s b/libsrc/apple2/get_iigs_speed.s
index 1915d7773..b960516fa 100644
--- a/libsrc/apple2/get_iigs_speed.s
+++ b/libsrc/apple2/get_iigs_speed.s
@@ -16,7 +16,7 @@ _get_iigs_speed:
         lda     CYAREG          ; Check current setting
         bpl     :+
         lda     #SPEED_FAST
-        ldx     #$00
+        ldx     #>$0000
         rts
         .assert SPEED_SLOW = 0, error
 :       jmp     return0         ; SPEED_SLOW
diff --git a/libsrc/apple2/getdevice.s b/libsrc/apple2/getdevice.s
index 0c674cad0..f3b0d5a86 100644
--- a/libsrc/apple2/getdevice.s
+++ b/libsrc/apple2/getdevice.s
@@ -30,5 +30,5 @@ next:   inx
         bne     next
 
 done:   txa
-        ldx     #$00
+        ldx     #>$0000
         rts
diff --git a/libsrc/apple2/joy/a2.stdjoy.s b/libsrc/apple2/joy/a2.stdjoy.s
index 11be52eb4..b5e7a311b 100644
--- a/libsrc/apple2/joy/a2.stdjoy.s
+++ b/libsrc/apple2/joy/a2.stdjoy.s
@@ -92,7 +92,7 @@ COUNT:
         bvc     noiic           ; Not $4x
         dex                     ; Only one joystick for the //c
 noiic:  txa                     ; Number of joysticks we support
-        ldx     #$00
+        ldx     #>$0000
         rts
 
 ; READ routine. Read a particular joystick passed in A.
@@ -170,5 +170,5 @@ nogs2:  lda     #$00            ; 0 0 0 0 0 0 0 0
 
         ; Finalize
         eor     #%00010100      ; BTN_2 BTN_1 DOWN UP RIGHT LEFT 0 0
-        ldx     #$00
+        ldx     #>$0000
         rts
diff --git a/libsrc/apple2/mou/a2.stdmou.s b/libsrc/apple2/mou/a2.stdmou.s
index 9b84c2f53..e48abbb41 100644
--- a/libsrc/apple2/mou/a2.stdmou.s
+++ b/libsrc/apple2/mou/a2.stdmou.s
@@ -353,7 +353,7 @@ SHOW:
 ; BUTTONS: Return the button mask in A/X.
 BUTTONS:
         lda     info + MOUSE_INFO::BUTTONS
-        ldx     #$00
+        ldx     #>$0000
         rts
 
 ; POS: Return the mouse position in the MOUSE_POS struct pointed to by ptr1.
diff --git a/libsrc/apple2/open.s b/libsrc/apple2/open.s
index 38793a13e..7ece7f18d 100644
--- a/libsrc/apple2/open.s
+++ b/libsrc/apple2/open.s
@@ -209,7 +209,7 @@ done:   lda     tmp1            ; Restore fd
         jsr     popname         ; Preserves A
 
         ; Return success
-        ldx     #$00
+        ldx     #>$0000
         stx     ___oserror
         rts
 
diff --git a/libsrc/apple2/oserror.s b/libsrc/apple2/oserror.s
index 5f523340f..db4f146cd 100644
--- a/libsrc/apple2/oserror.s
+++ b/libsrc/apple2/oserror.s
@@ -23,7 +23,7 @@ ___osmaperrno:
 
         ; Found the code
 :       lda     ErrTab-1,x
-        ldx     #$00            ; High byte always zero
+        ldx     #>$0000
         rts
 
         .rodata
diff --git a/libsrc/apple2/revers.s b/libsrc/apple2/revers.s
index 83fcb2ae7..86dfd0d19 100644
--- a/libsrc/apple2/revers.s
+++ b/libsrc/apple2/revers.s
@@ -18,5 +18,5 @@ normal: dex                     ; $00->$FF, $40->$3F
         stx     INVFLG          ; Save new flag value
         bmi     :+              ; Jump if current value is $FF (normal)
         lda     #$01            ; Return "inverse"
-:       ldx     #$00
+:       ldx     #>$0000
         rts
diff --git a/libsrc/apple2/ser/a2.gs.s b/libsrc/apple2/ser/a2.gs.s
index ea3e54cc1..3ad899fc2 100644
--- a/libsrc/apple2/ser/a2.gs.s
+++ b/libsrc/apple2/ser/a2.gs.s
@@ -295,7 +295,7 @@ SER_CLOSE:
         bcc     IIgs
 
         lda     #SER_ERR_NO_DEVICE      ; Not a IIgs
-        ldx     #$00                    ; Promote char return value
+        ldx     #>$0000
         rts
 
 IIgs:
@@ -500,7 +500,7 @@ BaudOK:
 
 SetupOut:
         plp                             ; Reenable interrupts if needed
-        ldx     #$00                    ; Promote char return value
+        ldx     #>$0000
         sty     Opened
         rts
 
@@ -539,7 +539,7 @@ SER_GET:
         rts
 NoData:
         lda     #SER_ERR_NO_DATA
-        ldx     #$00                    ; Promote char return value
+        ldx     #>$0000
         rts
 
 ;----------------------------------------------------------------------------
@@ -560,7 +560,7 @@ SER_PUT:
 :       ldy     SendFreeCnt             ; Do we have room to store byte?
         bne     :+
         lda     #SER_ERR_OVERFLOW
-        ldx     #$00
+        ldx     #>$0000
         rts
 
 :       ldy     SendTail                ; Put byte into send buffer & send
@@ -571,7 +571,7 @@ SER_PUT:
         jsr     TryToSend
         lda     #SER_ERR_OK
         .assert SER_ERR_OK = 0, error
-        tax
+        tax                             ; Promote char return value
         rts
 
 ;----------------------------------------------------------------------------
@@ -608,11 +608,11 @@ SER_IOCTL:
 
         stx     Channel
         .assert SER_ERR_OK = 0, error
-        tax
+        tax                             ; Promote char return value
         rts
 
 :       lda     #SER_ERR_INV_IOCTL
-        ldx     #$00                    ; Promote char return value
+        ldx     #>$0000
         rts
 
 ;----------------------------------------------------------------------------
diff --git a/libsrc/apple2/ser/a2.ssc.s b/libsrc/apple2/ser/a2.ssc.s
index 88dc4572c..488a32540 100644
--- a/libsrc/apple2/ser/a2.ssc.s
+++ b/libsrc/apple2/ser/a2.ssc.s
@@ -345,7 +345,7 @@ BaudOK: sta     tmp1
         stx     Index           ; Mark port as open
         lda     #SER_ERR_OK
 Out:
-        ldx     #$00            ; Promote char return value
+        ldx     #>$0000
         rts
 
 ;----------------------------------------------------------------------------
@@ -360,7 +360,7 @@ SER_GET:
         cmp     #$FF
         bne     :+
         lda     #SER_ERR_NO_DATA
-        ldx     #$00            ; Promote char return value
+        ldx     #>$0000
         rts
 
 :       ldy     Stopped         ; Check for flow stopped
@@ -408,7 +408,7 @@ SER_PUT:
         ldy     SendFreeCnt     ; Reload SendFreeCnt after TryToSend
         bne     :+
         lda     #SER_ERR_OVERFLOW
-        ldx     #$00            ; Promote char return value
+        ldx     #>$0000
         rts
 
 :       ldy     SendTail        ; Put byte into send buffer
@@ -456,7 +456,7 @@ SER_IOCTL:
         rts
 
 :       lda     #SER_ERR_INV_IOCTL
-        ldx     #$00            ; Promote char return value
+        ldx     #>$0000
         rts
 
 ;----------------------------------------------------------------------------
diff --git a/libsrc/apple2/set_iigs_speed.s b/libsrc/apple2/set_iigs_speed.s
index 5e2f2f722..f13e8ab6a 100644
--- a/libsrc/apple2/set_iigs_speed.s
+++ b/libsrc/apple2/set_iigs_speed.s
@@ -25,5 +25,5 @@ _set_iigs_speed:
 set_speed:
         sta     CYAREG
         txa
-        ldx     #$00
+        ldx     #>$0000
         rts
diff --git a/libsrc/apple2/stat.s b/libsrc/apple2/stat.s
index f655b3e3f..e0564ae0c 100644
--- a/libsrc/apple2/stat.s
+++ b/libsrc/apple2/stat.s
@@ -121,7 +121,7 @@ eoferr:
         beq     done
         lda     #$FF
 done:
-        tax
+        tax                     ; Promote char return value
         rts
 
         .bss
diff --git a/libsrc/apple2/tgi/a2.hi.s b/libsrc/apple2/tgi/a2.hi.s
index aeb24f6be..1d5bdb68b 100644
--- a/libsrc/apple2/tgi/a2.hi.s
+++ b/libsrc/apple2/tgi/a2.hi.s
@@ -342,7 +342,7 @@ GETPIXEL:
         lda     #$03            ; 3 (white)
 :       bcc     :+
         adc     #$03            ; += 4 (black -> black2, white -> white2)
-:       ldx     #$00
+:       ldx     #>$0000
         bit     $C080           ; Switch in LC bank 2 for R/O
         rts
 
diff --git a/libsrc/apple2/tgi/a2.lo.s b/libsrc/apple2/tgi/a2.lo.s
index 6d1c6aa4a..8b00c5d20 100644
--- a/libsrc/apple2/tgi/a2.lo.s
+++ b/libsrc/apple2/tgi/a2.lo.s
@@ -321,7 +321,7 @@ GETPIXEL:
         jsr     SCRN
         tax
         lda     COL2TGI,x
-        ldx     #$00
+        ldx     #>$0000
         bit     $C080           ; Switch in LC bank 2 for R/O
         rts
 
diff --git a/libsrc/apple2/wherey.s b/libsrc/apple2/wherey.s
index daacaaba7..a3843f606 100644
--- a/libsrc/apple2/wherey.s
+++ b/libsrc/apple2/wherey.s
@@ -12,5 +12,5 @@ _wherey:
         lda     CV
         sec
         sbc     WNDTOP
-        ldx     #$00
+        ldx     #>$0000
         rts