diff --git a/exwm-core.el b/exwm-core.el
index 55fbecd..39928e1 100644
--- a/exwm-core.el
+++ b/exwm-core.el
@@ -150,11 +150,12 @@ least SECS seconds later."
                         ,function
                         ,@args))
 
-(defconst exwm--client-event-mask (logior xcb:EventMask:StructureNotify
-                                          xcb:EventMask:PropertyChange
-                                          (if mouse-autoselect-window
-                                              xcb:EventMask:EnterWindow 0))
-  "Event mask set on all managed windows.")
+(defun exwm--get-client-event-mask ()
+  "Return event mask set on all managed windows."
+  (logior xcb:EventMask:StructureNotify
+          xcb:EventMask:PropertyChange
+          (if mouse-autoselect-window
+              xcb:EventMask:EnterWindow 0)))
 
 ;; Internal variables
 (defvar-local exwm--id nil)               ;window ID
diff --git a/exwm-floating.el b/exwm-floating.el
index b7430d7..7ac2c27 100644
--- a/exwm-floating.el
+++ b/exwm-floating.el
@@ -342,7 +342,7 @@ This is also used by X window containers.")
         (xcb:+request exwm--connection
             (make-instance 'xcb:ChangeWindowAttributes
                            :window id :value-mask xcb:CW:EventMask
-                           :event-mask exwm--client-event-mask))
+                           :event-mask (exwm--get-client-event-mask)))
         ;; Reparent the floating frame back to the root window.
         (let ((frame-id (frame-parameter exwm--floating-frame 'exwm-outer-id))
               (frame-container (frame-parameter exwm--floating-frame
diff --git a/exwm-layout.el b/exwm-layout.el
index 52fd08e..9ef516b 100644
--- a/exwm-layout.el
+++ b/exwm-layout.el
@@ -158,7 +158,7 @@
       (xcb:+request exwm--connection
           (make-instance 'xcb:ChangeWindowAttributes
                          :window id :value-mask xcb:CW:EventMask
-                         :event-mask exwm--client-event-mask))
+                         :event-mask (exwm--get-client-event-mask)))
       (exwm-layout--set-state id xcb:icccm:WM_STATE:IconicState)
       (exwm-layout--auto-iconify)
       (xcb:flush exwm--connection))))
diff --git a/exwm-manage.el b/exwm-manage.el
index b41512c..5c32284 100644
--- a/exwm-manage.el
+++ b/exwm-manage.el
@@ -195,7 +195,7 @@ You can still make the X windows floating afterwards."
     (when (xcb:+request-checked+request-check exwm--connection
               (make-instance 'xcb:ChangeWindowAttributes
                              :window id :value-mask xcb:CW:EventMask
-                             :event-mask exwm--client-event-mask))
+                             :event-mask (exwm--get-client-event-mask)))
       (throw 'return 'dead))
     ;; Add this X window to save-set.
     (xcb:+request exwm--connection
@@ -257,7 +257,7 @@ You can still make the X windows floating afterwards."
                                      exwm-window-type)
                                ;; Listen for PropertyChange (struts) and
                                ;; UnmapNotify/DestroyNotify event of the dock.
-                               exwm--client-event-mask
+                               (exwm--get-client-event-mask)
                              xcb:EventMask:NoEvent)))
         ;; The window needs to be mapped
         (xcb:+request exwm--connection