diff --git a/gnu/services/xorg.scm b/gnu/services/xorg.scm
index db1d808715..1988cfa6a0 100644
--- a/gnu/services/xorg.scm
+++ b/gnu/services/xorg.scm
@@ -147,7 +147,7 @@ (define (slim.cfg)
 
 # The login command.  '%session' is replaced by the chosen session name, one
 # of the names specified in the 'sessions' setting: 'wmaker', 'xfce', etc.
-login_cmd  exec " xinitrc "%session
+login_cmd  exec " xinitrc " %session
 sessions   wmaker,ratpoison
 
 halt_cmd " dmd "/sbin/halt