diff --git a/src/iordef.h b/src/iordef.h
index a47844d..9108a1c 100644
--- a/src/iordef.h
+++ b/src/iordef.h
@@ -8,6 +8,10 @@
 #ifndef _IORDEF_H
 #define _IORDEF_H
 
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
 #ifdef _WIN32
 #   define _CRT_SECURE_NO_WARNINGS
 #   define _CRT_RAND_S