diff --git a/sys/include/net/nanocoap.h b/sys/include/net/nanocoap.h
index 563902ea1a..9313a4f37a 100644
--- a/sys/include/net/nanocoap.h
+++ b/sys/include/net/nanocoap.h
@@ -463,7 +463,7 @@ void coap_pkt_init(coap_pkt_t *pkt, uint8_t *buf, size_t len, size_t header_len)
  *
  * @returns     amount of bytes written to @p buf
  */
-size_t coap_put_option(uint8_t *buf, uint16_t lastonum, uint16_t onum, uint8_t *odata, size_t olen);
+size_t coap_put_option(uint8_t *buf, uint16_t lastonum, uint16_t onum, const uint8_t *odata, size_t olen);
 
 /**
  * @brief   Insert content type option into buffer
@@ -656,6 +656,23 @@ size_t coap_put_block1_ok(uint8_t *pkt_pos, coap_block1_t *block1, uint16_t last
  */
 ssize_t coap_opt_add_string(coap_pkt_t *pkt, uint16_t optnum, const char *string, char separator);
 
+/**
+ * @brief   Encode the given buffer as an opaque data option into pkt
+ *
+ * @post pkt.payload advanced to first byte after option(s)
+ * @post pkt.payload_len reduced by option(s) length
+ *
+ * @param[in,out] pkt         pkt referencing target buffer
+ * @param[in]     optnum      option number to use
+ * @param[in]     val         pointer to the value to be set
+ * @param[in]     val_len     length of val
+ *
+ * @return        number of bytes written to buffer
+ * @return        <0 on error
+ * @return        -ENOSPC if no available options
+ */
+ssize_t coap_opt_add_opaque(coap_pkt_t *pkt, uint16_t optnum, const uint8_t *val, size_t val_len);
+
 /**
  * @brief   Encode the given uint option into pkt
  *
diff --git a/sys/net/application_layer/nanocoap/nanocoap.c b/sys/net/application_layer/nanocoap/nanocoap.c
index 126b12e3dd..b1d2085c88 100644
--- a/sys/net/application_layer/nanocoap/nanocoap.c
+++ b/sys/net/application_layer/nanocoap/nanocoap.c
@@ -566,7 +566,7 @@ static unsigned _put_delta_optlen(uint8_t *buf, unsigned offset, unsigned shift,
     return offset;
 }
 
-size_t coap_put_option(uint8_t *buf, uint16_t lastonum, uint16_t onum, uint8_t *odata, size_t olen)
+size_t coap_put_option(uint8_t *buf, uint16_t lastonum, uint16_t onum, const uint8_t *odata, size_t olen)
 {
     assert(lastonum <= onum);
 
@@ -728,7 +728,7 @@ size_t coap_opt_put_string(uint8_t *buf, uint16_t lastonum, uint16_t optnum,
 }
 
 /* Common functionality for addition of an option */
-static ssize_t _add_opt_pkt(coap_pkt_t *pkt, uint16_t optnum, uint8_t *val,
+static ssize_t _add_opt_pkt(coap_pkt_t *pkt, uint16_t optnum, const uint8_t *val,
                             size_t val_len)
 {
     if (pkt->options_len >= NANOCOAP_NOPTS_MAX) {
@@ -802,6 +802,11 @@ ssize_t coap_opt_add_string(coap_pkt_t *pkt, uint16_t optnum, const char *string
     return write_len;
 }
 
+ssize_t coap_opt_add_opaque(coap_pkt_t *pkt, uint16_t optnum, const uint8_t *val, size_t val_len)
+{
+    return _add_opt_pkt(pkt, optnum, val, val_len);
+}
+
 ssize_t coap_opt_add_uint(coap_pkt_t *pkt, uint16_t optnum, uint32_t value)
 {
     uint32_t tmp = value;