diff --git a/sys/crypto/modes/ccm.c b/sys/crypto/modes/ccm.c
index 3f5a428820..322a568fd3 100644
--- a/sys/crypto/modes/ccm.c
+++ b/sys/crypto/modes/ccm.c
@@ -43,6 +43,12 @@ static int ccm_compute_cbc_mac(cipher_t *cipher, const uint8_t iv[16],
     block_size = cipher_get_block_size(cipher);
     memmove(mac, iv, 16);
     offset = 0;
+
+    /* no input message */
+    if(length == 0) {
+        return 0;
+    }
+
     do {
         uint8_t block_size_input = (length - offset > block_size) ?
                                    block_size : length - offset;
diff --git a/sys/include/crypto/modes/ccm.h b/sys/include/crypto/modes/ccm.h
index 4c81593ae7..9900b8407e 100644
--- a/sys/include/crypto/modes/ccm.h
+++ b/sys/include/crypto/modes/ccm.h
@@ -57,10 +57,12 @@ extern "C" {
  * @param nonce_len        Length of the nonce in octets
  *                         (maximum: 15-length_encoding)
  * @param input            pointer to input data to encrypt
- * @param input_len        length of the input data, max 2^32
+ * @param input_len        length of the input data, [0, 2^32]
  * @param output           pointer to allocated memory for encrypted data. It
  *                         has to be of size data_len + mac_length.
- * @return                 Length of encrypted data on a successful encryption
+ *
+ * @return                 Length of encrypted data on a successful encryption,
+ *                         can be 0 if input_len=0 (no plaintext)
  * @return                 A negative error code if something went wrong
  */
 int cipher_encrypt_ccm(cipher_t *cipher,
@@ -85,11 +87,12 @@ int cipher_encrypt_ccm(cipher_t *cipher,
  * @param nonce_len        Length of the nonce in octets
  *                         (maximum: 15-length_encoding)
  * @param input            pointer to input data to decrypt
- * @param input_len        length of the input data, max 2^32
+ * @param input_len        length of the input data, [0, 2^32]
  * @param output           pointer to allocated memory for decrypted data. It
  *                         has to be of size data_len - mac_length.
  *
- * @return                 Length of the decrypted data on a successful decryption
+ * @return                 Length of the decrypted data on a successful decryption,
+ *                         can be 0 if only auth_data and MAC is present.
  * @return                 A negative error code if something went wrong
  */
 int cipher_decrypt_ccm(cipher_t *cipher,