Fix typo.
diff --git a/src/chapters/installing.xml b/src/chapters/installing.xml
index 5508976..69ae3bd 100644
--- a/src/chapters/installing.xml
+++ b/src/chapters/installing.xml
@@ -932,7 +932,7 @@
<uri>/guacamole/</uri> to <uri>/new-path/</uri>, the same path specified when
the location was declared.</para>
<para>Be careful when specifying the URL in the <parameter>ProxyPassReverse</parameter>
- directive. The protocol or the URL <emphasis>MUST</emphasis> match the protocol that
+ directive. The protocol of the URL <emphasis>MUST</emphasis> match the protocol that
will be used to connect to to Apache, even if it differs from the protocol being
used to connect to Tomcat.</para>
</section>
