diff --git a/reference/mongo/mongoclient.xml b/reference/mongo/mongoclient.xml
index 9543b0aac6..27e22a0356 100644
--- a/reference/mongo/mongoclient.xml
+++ b/reference/mongo/mongoclient.xml
@@ -166,7 +166,7 @@ $db = $m->foo; // get the database named "foo"
      </varlistentry>
      <varlistentry xml:id="mongoclient.constants.rpprimary">
       <term><constant>MongoClient::RP_PRIMARY</constant></term>
-      <term><constant>0</constant></term>
+      <term><constant>"primary"</constant></term>
       <listitem>
        <simpara>
         <link linkend="mongo.readpreferences">Read preference</link> for the
@@ -176,7 +176,7 @@ $db = $m->foo; // get the database named "foo"
      </varlistentry>
      <varlistentry xml:id="mongoclient.constants.rpprimarypreferred">
       <term><constant>MongoClient::RP_PRIMARY_PREFERRED</constant></term>
-      <term><constant>1</constant></term>
+      <term><constant>"primaryPreferred"</constant></term>
       <listitem>
        <simpara>
         <link linkend="mongo.readpreferences">Read preference</link> for
@@ -186,7 +186,7 @@ $db = $m->foo; // get the database named "foo"
      </varlistentry>
      <varlistentry xml:id="mongoclient.constants.rpsecondary">
       <term><constant>MongoClient::RP_SECONDARY</constant></term>
-      <term><constant>2</constant></term>
+      <term><constant>"secondary"</constant></term>
       <listitem>
        <simpara>
         <link linkend="mongo.readpreferences">Read preference</link> for a
@@ -196,7 +196,7 @@ $db = $m->foo; // get the database named "foo"
      </varlistentry>
      <varlistentry xml:id="mongoclient.constants.rpsecondarypreferred">
       <term><constant>MongoClient::RP_SECONDARY_PREFERRED</constant></term>
-      <term><constant>3</constant></term>
+      <term><constant>"secondaryPreferred"</constant></term>
       <listitem>
        <simpara>
         <link linkend="mongo.readpreferences">Read preference</link> for
@@ -206,7 +206,7 @@ $db = $m->foo; // get the database named "foo"
      </varlistentry>
      <varlistentry xml:id="mongoclient.constants.rpnearest">
       <term><constant>MongoClient::RP_NEAREST</constant></term>
-      <term><constant>4</constant></term>
+      <term><constant>"nearest"</constant></term>
       <listitem>
        <simpara>
         <link linkend="mongo.readpreferences">Read preference</link> for the