diff --git a/modules/tools/pdf/config.el b/modules/tools/pdf/config.el
index d1385d5d6..a7d862f2a 100644
--- a/modules/tools/pdf/config.el
+++ b/modules/tools/pdf/config.el
@@ -45,7 +45,7 @@
 
   ;; Handle PDF-tools related popups better
   (set-popup-rules!
-    '(("^\\*Outline*" :side 'right :size 40 :select nil)
+    '(("^\\*Outline*" :side right :size 40 :select nil)
       ("\\(?:^\\*Contents\\|'s annots\\*$\\)" :ignore t)))
 
   ;; The mode-line does serve any useful purpose is annotation windows