diff --git a/src/backend/port/BSD44_derived/dl.c b/src/backend/port/BSD44_derived/dl.c
index 394fb8a2e0..73e9e48dbc 100644
--- a/src/backend/port/BSD44_derived/dl.c
+++ b/src/backend/port/BSD44_derived/dl.c
@@ -38,6 +38,7 @@ static char sccsid[] = "@(#)dl.c	5.4 (Berkeley) 2/23/91";
 #include <sys/types.h>
 #include <nlist.h>
 #include <link.h>
+#include <dlfcn.h>
 
 #include <stdio.h>
 #include <stdlib.h>