diff --git a/lib/checksum.c b/lib/checksum.c
index 8c0ea52..201da59 100644
--- a/lib/checksum.c
+++ b/lib/checksum.c
@@ -7,10 +7,12 @@
  */
 
 #include <zebra.h>
+#include "checksum.h"
 
-int				/* return checksum in low-order 16 bits */
-in_cksum(u_short *ptr, int nbytes)
+int			/* return checksum in low-order 16 bits */
+in_cksum(void *parg, int nbytes)
 {
+	u_short *ptr = parg;
 	register long		sum;		/* assumes long == 32 bits */
 	u_short			oddbyte;
 	register u_short	answer;		/* assumes u_short == 16 bits */