diff --git a/src/include/libpq/pqmq.h b/src/include/libpq/pqmq.h
index 6bb24d9928..f8e68c9cb0 100644
--- a/src/include/libpq/pqmq.h
+++ b/src/include/libpq/pqmq.h
@@ -13,6 +13,7 @@
 #ifndef PQMQ_H
 #define PQMQ_H
 
+#include "lib/stringinfo.h"
 #include "storage/shm_mq.h"
 
 extern void	pq_redirect_to_shm_mq(shm_mq *, shm_mq_handle *);