diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index cc9185ca8fd1..0f6e60a9c308 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -422,7 +422,7 @@ struct sctp_cookie {
 	__u32 adaptation_ind;
 
 	__u8 auth_random[sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH];
-	__u8 auth_hmacs[SCTP_AUTH_NUM_HMACS + 2];
+	__u8 auth_hmacs[SCTP_AUTH_NUM_HMACS * sizeof(__u16) + 2];
 	__u8 auth_chunks[sizeof(sctp_paramhdr_t) + SCTP_AUTH_MAX_CHUNKS];
 
 	/* This is a shim for my peer's INIT packet, followed by