diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index a94743b587b..c0b89a3c01c 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -1838,7 +1838,7 @@ psql "dbname=postgres replication=database" -c "IDENTIFY_SYSTEM;"
        </varlistentry>
 
        <varlistentry>
-        <term><literal>timeline</literal> (<type>int4</type>)</term>
+        <term><literal>timeline</literal> (<type>int8</type>)</term>
         <listitem>
          <para>
           Current timeline ID. Also useful to check that the standby is
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index e42671722a8..fa60c92e13a 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -444,7 +444,7 @@ IdentifySystem(void)
 	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "systemid",
 							  TEXTOID, -1, 0);
 	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "timeline",
-							  INT4OID, -1, 0);
+							  INT8OID, -1, 0);
 	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "xlogpos",
 							  TEXTOID, -1, 0);
 	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 4, "dbname",