diff --git a/sys/netinet/sctp_crc32.c b/sys/netinet/sctp_crc32.c
index 9e17637d74d6..816a72bbea7b 100644
--- a/sys/netinet/sctp_crc32.c
+++ b/sys/netinet/sctp_crc32.c
@@ -90,7 +90,7 @@ sctp_calculate_cksum_cb(void *arg, void *data, u_int len)
  * it is compiled on a kernel with SCTP support.
  */
 uint32_t
-sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
+sctp_calculate_cksum(struct mbuf *m, int32_t offset)
 {
 	uint32_t base;
 	int len;
diff --git a/sys/netinet/sctp_crc32.h b/sys/netinet/sctp_crc32.h
index 6b86074b696f..96ab7b96b6e4 100644
--- a/sys/netinet/sctp_crc32.h
+++ b/sys/netinet/sctp_crc32.h
@@ -39,7 +39,7 @@ __FBSDID("$FreeBSD$");
 #define _NETINET_SCTP_CRC32_H_
 
 #if defined(_KERNEL)
-uint32_t sctp_calculate_cksum(struct mbuf *, uint32_t);
+uint32_t sctp_calculate_cksum(struct mbuf *, int32_t);
 #if defined(SCTP) || defined(SCTP_SUPPORT)
 void sctp_delayed_cksum(struct mbuf *, uint32_t offset);
 #endif