diff --git a/compat/vis.c b/compat/vis.c
index 9ebdc72..086d93b 100644
--- a/compat/vis.c
+++ b/compat/vis.c
@@ -28,6 +28,8 @@
  * SUCH DAMAGE.
  */
 
+#include "../config.h"
+
 #include <sys/types.h>
 #include <errno.h>
 #include <ctype.h>