Add missing "}".
diff --git a/Doc/mac/undoc.tex b/Doc/mac/undoc.tex
index d092158..0683289 100644
--- a/Doc/mac/undoc.tex
+++ b/Doc/mac/undoc.tex
@@ -85,7 +85,7 @@
 dialogs and menus, without requiring special case code for when the
 script is run under MacPython, as a MacPython applet or under OSX Python.
 
-\section{\module{Nav --- NavServices calls}
+\section{\module{Nav} --- NavServices calls}
 \declaremodule{standard}{Nac}
   \platform{Mac}
 \modulesynopsis{Interface to Navigation Services}