diff --git a/exwm-randr.el b/exwm-randr.el
index c1d2bf5..37f40f1 100644
--- a/exwm-randr.el
+++ b/exwm-randr.el
@@ -210,7 +210,8 @@ the first one in result being the primary output."
   ;; Prevent frame parameters introduced by this module from being
   ;; saved/restored.
   (dolist (i '(exwm-randr-output))
-    (push (cons i :never) frameset-filter-alist)))
+    (unless (assq i frameset-filter-alist)
+      (push (cons i :never) frameset-filter-alist))))
 
 (defun exwm-randr--exit ()
   "Exit the RandR module."
diff --git a/exwm-workspace.el b/exwm-workspace.el
index a999719..f1ca8d5 100644
--- a/exwm-workspace.el
+++ b/exwm-workspace.el
@@ -1555,7 +1555,8 @@ applied to all subsequently created X frames."
   ;; saved/restored.
   (dolist (i '(exwm-active exwm-outer-id exwm-id exwm-container exwm-geometry
                            exwm-selected-window exwm-urgency fullscreen))
-    (push (cons i :never) frameset-filter-alist)))
+    (unless (assq i frameset-filter-alist)
+      (push (cons i :never) frameset-filter-alist))))
 
 (defun exwm-workspace--exit ()
   "Exit the workspace module."