diff --git a/core.c b/core.c
index 9247b53..cc39dcf 100644
--- a/core.c
+++ b/core.c
@@ -155,7 +155,7 @@
 	return buf;
 }
 
-int mctp_pktbuf_push(struct mctp_pktbuf *pkt, void *data, size_t len)
+int mctp_pktbuf_push(struct mctp_pktbuf *pkt, const void *data, size_t len)
 {
 	void *p;