diff --git a/modules/ui/treemacs/config.el b/modules/ui/treemacs/config.el
index 62e3e6ddb..4ee9a8e0b 100644
--- a/modules/ui/treemacs/config.el
+++ b/modules/ui/treemacs/config.el
@@ -29,6 +29,14 @@ This must be set before `treemacs' has loaded.")
   ;; Don't follow the cursor (it's more disruptive/jarring than helpful as a default)
   (treemacs-follow-mode -1)
 
+  ;; HACK: persp-mode changed the signature for `persp-activated-functions', but
+  ;;   treemacs hasn't updated its usage yet.
+  ;; REVIEW: PR upstream
+  (remove-hook 'persp-activated-functions #'treemacs--remove-treemacs-window-in-new-frames)
+  (add-hook! 'persp-activated-functions
+    (defun +treemacs--remove-treemacs-window-in-new-frames-h (type &rest _)
+      (treemacs--remove-treemacs-window-in-new-frames type)))
+
   (set-popup-rule! "^ ?\\*Treemacs" :ignore t)
   (when +treemacs-git-mode
     ;; If they aren't supported, fall back to simpler methods