diff --git a/os/strndup.c b/os/strndup.c
index b604b9bac..e0eddf13d 100644
--- a/os/strndup.c
+++ b/os/strndup.c
@@ -27,6 +27,10 @@
  * SUCH DAMAGE.
  */
 
+#ifdef HAVE_DIX_CONFIG_H
+#include <dix-config.h>
+#endif
+
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>