diff --git a/library/lua/gui.lua b/library/lua/gui.lua
index dc08506d7..d870399a3 100644
--- a/library/lua/gui.lua
+++ b/library/lua/gui.lua
@@ -693,6 +693,8 @@ end
 -- Z-order swapping screen --
 -----------------------------
 
+local zscreen_inhibit_mouse_l = false
+
 ZScreen = defclass(ZScreen, Screen)
 ZScreen.ATTRS{
     initial_pause=true,
@@ -754,7 +756,7 @@ function ZScreen:onInput(keys)
         if keys._MOUSE_L_DOWN then
             -- note we can't clear mouse_lbut here. otherwise we break dragging,
             df.global.enabler.mouse_lbut_down = 0
-            self.inhibit_mouse_l = true
+            zscreen_inhibit_mouse_l = true
         end
         if keys._MOUSE_R_DOWN then
             df.global.enabler.mouse_rbut_down = 0
@@ -773,11 +775,11 @@ function ZScreen:onInput(keys)
         df.global.enabler.mouse_rbut = 0
         return
     else
-        if self.inhibit_mouse_l then
+        if zscreen_inhibit_mouse_l then
             if keys._MOUSE_L then
                 return
             else
-                self.inhibit_mouse_l = nil
+                zscreen_inhibit_mouse_l = false
             end
         end
         local passit = self.pass_pause and keys.D_PAUSE