diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 3bd9e68e6ce4..96fd3c7c5ac3 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -6066,7 +6066,7 @@ psql "dbname=postgres replication=database" -c "IDENTIFY_SYSTEM;"
 
          In addition to the above, other parameters may be listed.
          Parameter names beginning with <literal>_pq_.</literal> are
-         reserved for use as protocol extensions, while others are
+         reserved for use as protocol options, while others are
          treated as run-time parameters to be set at backend start
          time.  Such settings will be applied during backend start
          (after parsing the command-line arguments if any) and will
diff --git a/src/backend/backup/basebackup_copy.c b/src/backend/backup/basebackup_copy.c
index a284ce318ff7..d1d76495c835 100644
--- a/src/backend/backup/basebackup_copy.c
+++ b/src/backend/backup/basebackup_copy.c
@@ -9,7 +9,7 @@
  * the course of that single COPY OUT. Each CopyData message begins with a
  * type byte, allowing us to signal the start of a new archive, or the
  * manifest, by some means other than ending the COPY stream. This also allows
- * for future protocol extensions, since we can include arbitrary information
+ * for future protocol options, since we can include arbitrary information
  * in the message stream as long as we're certain that the client will know
  * what to do with it.
  *
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 95dd456f0764..0e0f626e1d6f 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -1439,8 +1439,8 @@ pqGetNegotiateProtocolVersion3(PGconn *conn)
 	if (num > 0)
 	{
 		appendPQExpBuffer(&conn->errorMessage,
-						  libpq_ngettext("protocol extension not supported by server: %s",
-										 "protocol extensions not supported by server: %s", num),
+						  libpq_ngettext("protocol option not supported by server: %s",
+										 "protocol options not supported by server: %s", num),
 						  buf.data);
 		appendPQExpBufferChar(&conn->errorMessage, '\n');
 	}