diff --git a/desk.acc/calculator.s b/desk.acc/calculator.s
index 7912c81..5504b4d 100644
--- a/desk.acc/calculator.s
+++ b/desk.acc/calculator.s
@@ -666,7 +666,6 @@ window_title:
 init:   sta     ALTZPON
         lda     LCBANK1
         lda     LCBANK1
-        MGTK_CALL MGTK::SetZP1, preserve_zp_params
         MGTK_CALL MGTK::OpenWindow, winfo
         MGTK_CALL MGTK::InitPort, grafport
         MGTK_CALL MGTK::SetPort, grafport
@@ -696,8 +695,9 @@ loop:   lda     adjust_txtptr_copied-1,x
         bne     loop
 .endproc
 
-        lda     #0              ; Turn off errors
-        sta     ERRFLG
+        lda     #0
+        sta     ERRFLG          ; Turn off errors
+        sta     SHIFT_SIGN_EXT  ; Zero before using FP ops
 
         copy16  #error_hook, COUT_HOOK ; set up FP error handler
 
@@ -772,7 +772,6 @@ ignore_click:
 exit:   MGTK_CALL MGTK::CloseWindow, closewindow_params
         DESKTOP_CALL DT_REDRAW_ICONS
         lda     ROMIN2
-        MGTK_CALL MGTK::SetZP1, overwrite_zp_params
 
 .proc do_close
         ;; Copy following routine to ZP and invoke it
diff --git a/desk.acc/eyes.s b/desk.acc/eyes.s
index 471cabb..967d231 100644
--- a/desk.acc/eyes.s
+++ b/desk.acc/eyes.s
@@ -187,8 +187,6 @@ grow_box_bitmap:
         lda     LCBANK1
         lda     LCBANK1
 
-        ;; Don't let MGTK smash zero page
-        MGTK_CALL MGTK::SetZP1, preserve_zp_params
         lda     #0
         sta     SHIFT_SIGN_EXT  ; Must zero before using FP ops
 
@@ -214,7 +212,6 @@ grow_box_bitmap:
 .proc exit
         MGTK_CALL MGTK::CloseWindow, winfo
         DESKTOP_CALL DT_REDRAW_ICONS
-        MGTK_CALL MGTK::SetZP1, overwrite_zp_params
         rts
 .endproc
 
diff --git a/desktop/desktop_main.s b/desktop/desktop_main.s
index a345f50..5100cfb 100644
--- a/desktop/desktop_main.s
+++ b/desktop/desktop_main.s
@@ -1559,10 +1559,7 @@ nope:   dex
         ;; Invoke it
         jsr     set_pointer_cursor
         jsr     reset_grafport3
-        ;;         MGTK_RELAY_CALL MGTK::SetZP1, zp_use_flag0
-        ;;         MGTK_RELAY_CALL MGTK::SetZP1, zp_use_flag1
         jsr     DA_LOAD_ADDRESS
-        ;;         MGTK_RELAY_CALL MGTK::SetZP1, zp_use_flag0
         lda     #0
         sta     running_da_flag
 
@@ -15542,7 +15539,6 @@ end:
         MGTK_RELAY_CALL MGTK::StartDeskTop, startdesktop_params
         jsr     desktop_main::set_mono_mode
         MGTK_RELAY_CALL MGTK::SetMenu, splash_menu
-        MGTK_RELAY_CALL MGTK::SetZP1, zp_use_flag0
         MGTK_RELAY_CALL MGTK::SetCursor, watch_cursor
         MGTK_RELAY_CALL MGTK::ShowCursor
         ;; fall through