diff --git a/include/coap/pdu.h b/include/coap/pdu.h
index e60dadca..7fec87ae 100644
--- a/include/coap/pdu.h
+++ b/include/coap/pdu.h
@@ -71,12 +71,12 @@
 #define COAP_OPTION_PROXY_SCHEME   39 /* C, String, 1-255 B, (none) */
 #define COAP_OPTION_SIZE1          60 /* E, uint, 0-4 B, (none) */
 
-/* option types from draft-ietf-coap-observe-09 */
+/* option types from RFC 7641 */
 
 #define COAP_OPTION_OBSERVE         6 /* E, empty/uint, 0 B/0-3 B, (none) */
 #define COAP_OPTION_SUBSCRIPTION  COAP_OPTION_OBSERVE
 
-/* selected option types from draft-core-block-04 */
+/* selected option types from RFC 7959 */
 
 #define COAP_OPTION_BLOCK2         23 /* C, uint, 0--3 B, (none) */
 #define COAP_OPTION_BLOCK1         27 /* C, uint, 0--3 B, (none) */