diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index be028d628b1..9b781c35002 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -6646,7 +6646,9 @@ PQport(const PGconn *conn)
 	if (!conn)
 		return NULL;
 
-	if (conn->connhost != NULL)
+	if (conn->connhost != NULL &&
+		conn->connhost[conn->whichhost].port != NULL &&
+		conn->connhost[conn->whichhost].port[0] != '\0')
 		return conn->connhost[conn->whichhost].port;
 
 	return "";
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index 668a5c87498..4b065486530 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -311,7 +311,8 @@ typedef struct pg_conn_host
 	pg_conn_host_type type;		/* type of host address */
 	char	   *host;			/* host name or socket path */
 	char	   *hostaddr;		/* host numeric IP address */
-	char	   *port;			/* port number (always provided) */
+	char	   *port;			/* port number (if NULL or empty, use
+								 * DEF_PGPORT[_STR]) */
 	char	   *password;		/* password for this host, read from the
 								 * password file; NULL if not sought or not
 								 * found in password file. */