diff --git a/res/res_config_pgsql.c b/res/res_config_pgsql.c
index 2e900d00de..0cf6d4ee1c 100644
--- a/res/res_config_pgsql.c
+++ b/res/res_config_pgsql.c
@@ -27,6 +27,7 @@
  ***/
 
 #include <stdlib.h>
+#include <stdio.h>
 #include <string.h>
 #include <libpq-fe.h>			/* PostgreSQL */