diff --git a/sample/sample-plugins/keying-material-exporter-demo/keyingmaterialexporter.c b/sample/sample-plugins/keying-material-exporter-demo/keyingmaterialexporter.c
index 1f47cb35..e2820418 100644
--- a/sample/sample-plugins/keying-material-exporter-demo/keyingmaterialexporter.c
+++ b/sample/sample-plugins/keying-material-exporter-demo/keyingmaterialexporter.c
@@ -29,6 +29,7 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <strings.h>
 #include <stdlib.h>
 
 #include "openvpn-plugin.h"