diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index dcbb704c6a5..74161970ab5 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -105,6 +105,8 @@ char	   *Unix_socket_group;
 /* Where the Unix socket files are (list of palloc'd strings) */
 static List *sock_paths = NIL;
 
+PQcommMethods *PqCommMethods;
+
 
 /*
  * Buffers for low-level I/O.
diff --git a/src/include/libpq/libpq.h b/src/include/libpq/libpq.h
index 409f3d7786e..2a61a9e143d 100644
--- a/src/include/libpq/libpq.h
+++ b/src/include/libpq/libpq.h
@@ -49,7 +49,7 @@ typedef struct
 	void (*endcopyout)(bool errorAbort);
 } PQcommMethods;
 
-PQcommMethods *PqCommMethods;
+extern PGDLLIMPORT PQcommMethods *PqCommMethods;
 
 #define pq_comm_reset()	(PqCommMethods->comm_reset())
 #define pq_flush() (PqCommMethods->flush())