diff --git a/doc/protocol.xml b/doc/protocol.xml
index 86534db74..7b384e4da 100644
--- a/doc/protocol.xml
+++ b/doc/protocol.xml
@@ -278,7 +278,7 @@
 
         <listitem>
           <para>
-            "<code>EXPRESSION1 AND EXPRESSION2 ...</code>": combine two or
+            "<code>(EXPRESSION1 AND EXPRESSION2 ...)</code>": combine two or
             more expressions with logical "and".
           </para>
         </listitem>