diff --git a/doc/tutorial/building-topologies.texi b/doc/tutorial/building-topologies.texi
index d129fde7e..365ce1883 100644
--- a/doc/tutorial/building-topologies.texi
+++ b/doc/tutorial/building-topologies.texi
@@ -574,7 +574,7 @@ nodes, which is 10.1.2.5 instead of the default case, 10.1.2.4.
 It is possible that you may not be satisfied with a trace file generated by
 a bystander in the CSMA network.  You may really want to get a trace from
 a single device and you may not be interested in any other traffic on the 
-network.  You can do this fairly easily/
+network.  You can do this fairly easily.
 
 Let's take a look at @code{scratch/mysecond.cc} and add that code enabling us
 to be more specific.  @code{ns-3} helpers provide methods that take a node