--- ray/src/px/ra_hexbit.c	2004/03/28 20:33:14	3.3
+++ ray/src/px/ra_hexbit.c	2018/03/20 18:45:04	3.4
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: ra_hexbit.c,v 3.3 2004/03/28 20:33:14 schorsch Exp $";
+static const char	RCSid[] = "$Id: ra_hexbit.c,v 3.4 2018/03/20 18:45:04 greg Exp $";
 #endif
 /*
  * Create a 4x1 hex bitmap from a Radiance picture.
@@ -9,6 +9,7 @@ static const char	RCSid[] = "$Id: ra_hexbit.c,v 3.3 20
 #include  <time.h>
 
 #include  "color.h"
+#include  "rtio.h"
 #include  "resolu.h"
 
 char  *progname;