diff --git a/lib.h b/lib.h
index 6cc58a2..b67cbcd 100644
--- a/lib.h
+++ b/lib.h
@@ -102,6 +102,7 @@ int hexstring2data(char *arg, unsigned char *data, int maxdlen);
  *
  */
 
+struct canfd_frame;
 int parse_canframe(char *cs, struct canfd_frame *cf);
 /*
  * Transfers a valid ASCII string describing a CAN frame into struct canfd_frame.