diff --git a/sys/include/net/nanocoap.h b/sys/include/net/nanocoap.h
index 88266dc424..91a57f1269 100644
--- a/sys/include/net/nanocoap.h
+++ b/sys/include/net/nanocoap.h
@@ -324,7 +324,7 @@ static inline uint8_t coap_code(unsigned cls, unsigned detail)
  *
  * @returns     message code class
  */
-static inline unsigned coap_get_code_class(coap_pkt_t *pkt)
+static inline unsigned coap_get_code_class(const coap_pkt_t *pkt)
 {
     return pkt->hdr->code >> 5;
 }
@@ -348,7 +348,7 @@ static inline unsigned coap_get_code_detail(const coap_pkt_t *pkt)
  *
  * @returns     message code in decimal format
  */
-static inline unsigned coap_get_code(coap_pkt_t *pkt)
+static inline unsigned coap_get_code(const coap_pkt_t *pkt)
 {
     return (coap_get_code_class(pkt) * 100) + coap_get_code_detail(pkt);
 }