diff --git a/gnu/services/xorg.scm b/gnu/services/xorg.scm
index 39eaeee0a4b..6be94d56143 100644
--- a/gnu/services/xorg.scm
+++ b/gnu/services/xorg.scm
@@ -67,7 +67,7 @@ Section \"Files\"
 EndSection
 
 Section \"ServerFlags\"
-  Option \"AllowMouseOpenFail\" \"on""
+  Option \"AllowMouseOpenFail\" \"on\"
 EndSection
 "))