diff --git a/contrib/postgres_fdw/option.c b/contrib/postgres_fdw/option.c
index fc3ce6a53a..4120c21d09 100644
--- a/contrib/postgres_fdw/option.c
+++ b/contrib/postgres_fdw/option.c
@@ -489,6 +489,9 @@ process_pgfdw_appname(const char *appname)
case 'a':
appendStringInfoString(&buf, application_name);
break;
+ case 'C':
+ appendStringInfoString(&buf, cluster_name);
+ break;
case 'd':
appendStringInfoString(&buf, MyProcPort->database_name);
break;
diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index 2bb31f1125..d7f545958c 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -983,6 +983,13 @@ postgres=# SELECT postgres_fdw_disconnect_all();
%a
Application name on local server
+
+ %C
+
+ Cluster name in local server
+ (see for details)
+
+
%u
User name on local server
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 6bb81707b0..f1bfe79feb 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -271,7 +271,7 @@ extern int temp_file_limit;
extern int num_temp_buffers;
-extern char *cluster_name;
+extern PGDLLIMPORT char *cluster_name;
extern PGDLLIMPORT char *ConfigFileName;
extern char *HbaFileName;
extern char *IdentFileName;