diff --git a/sys/include/net/nanocoap.h b/sys/include/net/nanocoap.h
index cf5d7fc64b..adcb940775 100644
--- a/sys/include/net/nanocoap.h
+++ b/sys/include/net/nanocoap.h
@@ -976,6 +976,9 @@ ssize_t coap_opt_add_opaque(coap_pkt_t *pkt, uint16_t optnum, const uint8_t *val
 /**
  * @brief   Adds a single Uri-Query option in the form 'key=value' into pkt
  *
+ * @note Use this only for null-terminated string. See @ref coap_opt_add_uquery2()
+ *       for non null-terminated string.
+ *
  * @param[in,out] pkt         The package that is being build
  * @param[in]     key         Key to add to the query string
  * @param[in]     val         Value to assign to @p key (may be NULL)
@@ -987,6 +990,24 @@ ssize_t coap_opt_add_opaque(coap_pkt_t *pkt, uint16_t optnum, const uint8_t *val
  */
 ssize_t coap_opt_add_uquery(coap_pkt_t *pkt, const char *key, const char *val);
 
+/**
+ * @brief   Adds a single Uri-Query option in the form 'key=value' into pkt
+ *
+ *
+ * @param[in,out] pkt         The package that is being build
+ * @param[in]     key         Key to add to the query string
+ * @param[in]     key_len     Length of @p key
+ * @param[in]     val         Value to assign to @p key (may be NULL)
+ * @param[in]     val_len     Length of @p val. 0 if @p val is NULL
+ *
+ * @pre     ((pkt != NULL) && (key != NULL) && (key_len > 0))
+ *
+ * @return  overall length of new query string
+ * @return  -1 on error
+ */
+ssize_t coap_opt_add_uquery2(coap_pkt_t *pkt, const char *key, size_t key_len,
+                             const char *val, size_t val_len);
+
 /**
  * @brief   Encode the given string as option(s) into pkt
  *
diff --git a/sys/net/application_layer/nanocoap/nanocoap.c b/sys/net/application_layer/nanocoap/nanocoap.c
index cac69efa12..a4f1a76f3c 100644
--- a/sys/net/application_layer/nanocoap/nanocoap.c
+++ b/sys/net/application_layer/nanocoap/nanocoap.c
@@ -846,27 +846,35 @@ ssize_t coap_opt_add_string(coap_pkt_t *pkt, uint16_t optnum, const char *string
     return write_len;
 }
 
-ssize_t coap_opt_add_uquery(coap_pkt_t *pdu, const char *key, const char *val)
+ssize_t coap_opt_add_uquery(coap_pkt_t *pkt, const char *key, const char *val)
 {
-    char qs[NANOCOAP_QS_MAX];
-    size_t len = strlen(key);
-    size_t val_len = (val) ? (strlen(val) + 1) : 0;
+    return coap_opt_add_uquery2(pkt, key, strlen(key), val, val ? strlen(val) : 0);
+}
 
-    /* test if the query string fits, account for the zero termination */
-    if ((len + val_len + 1) >= NANOCOAP_QS_MAX) {
+ssize_t coap_opt_add_uquery2(coap_pkt_t *pkt, const char *key, size_t key_len,
+                             const char *val, size_t val_len)
+{
+    assert(pkt);
+    assert(key);
+    assert(key_len);
+    assert(!val_len || (val && val_len));
+
+    char qs[NANOCOAP_QS_MAX];
+    size_t qs_len = key_len + ((val && val_len) ? (val_len + 1) : 0);
+
+    /* test if the query string fits */
+    if (qs_len >= NANOCOAP_QS_MAX) {
         return -1;
     }
 
-    memcpy(&qs[0], key, len);
-    if (val) {
-        qs[len] = '=';
-        /* the `=` character was already counted in `val_len`, so subtract it here */
-        memcpy(&qs[len + 1], val, (val_len - 1));
-        len += val_len;
+    memcpy(&qs[0], key, key_len);
+    if (val && val_len) {
+        qs[key_len] = '=';
+        memcpy(&qs[key_len + 1], val, val_len);
     }
-    qs[len] = '\0';
+    qs[qs_len] = '\0';
 
-    return coap_opt_add_string(pdu, COAP_OPT_URI_QUERY, qs, '&');
+    return coap_opt_add_string(pkt, COAP_OPT_URI_QUERY, qs, '&');
 }
 
 ssize_t coap_opt_add_opaque(coap_pkt_t *pkt, uint16_t optnum, const uint8_t *val, size_t val_len)