diff --git a/sys/crypto/modes/ccm.c b/sys/crypto/modes/ccm.c
index 9a75e547ad..a3f5c080f3 100644
--- a/sys/crypto/modes/ccm.c
+++ b/sys/crypto/modes/ccm.c
@@ -37,7 +37,8 @@ static inline int min(int a, int b)
 static int ccm_compute_cbc_mac(cipher_t *cipher, const uint8_t iv[16],
                         const uint8_t *input, size_t length, uint8_t *mac)
 {
-    uint8_t offset, block_size, mac_enc[16] = { 0 };
+    uint8_t block_size, mac_enc[16] = { 0 };
+    uint32_t offset;
 
     block_size = cipher_get_block_size(cipher);
     memmove(mac, iv, 16);
@@ -244,7 +245,8 @@ int cipher_decrypt_ccm(cipher_t *cipher,
     uint8_t nonce_counter[16] = { 0 }, mac_iv[16] = { 0 }, mac[16] = { 0 },
             mac_recv[16] = { 0 }, stream_block[16] = { 0 },
             zero_block[16] = { 0 },
-            plain_len, block_size;
+            block_size;
+    size_t plain_len;
 
     if (mac_length % 2 != 0  || mac_length < 4 || mac_length > 16) {
         return CCM_ERR_INVALID_MAC_LENGTH;
diff --git a/tests/sys_crypto/tests-crypto-modes-ccm.c b/tests/sys_crypto/tests-crypto-modes-ccm.c
index fb3ad69321..ba356171b7 100644
--- a/tests/sys_crypto/tests-crypto-modes-ccm.c
+++ b/tests/sys_crypto/tests-crypto-modes-ccm.c
@@ -864,8 +864,117 @@ static const uint8_t TEST_WYCHEPROOF_28_EXPECTED[] = {
 };
 static const size_t TEST_WYCHEPROOF_28_EXPECTED_LEN = 63;
 
+
+/* Manually created test vectors */
+/* This is neccessary, because no test vectors are published with input length > 256 */
+/* Data has been verified against BouncyCastle (.NET Core) and pycryptodome */
+
+static const uint8_t TEST_MANUAL_01_KEY[] = {
+    0x6D, 0x64, 0x80, 0x02, 0x92, 0xE5, 0x60, 0xB5,
+    0xA4, 0x93, 0x1A, 0x80, 0xC4, 0x8F, 0x43, 0x41
+};
+static const size_t TEST_MANUAL_01_KEY_LEN = 16;
+static const uint8_t TEST_MANUAL_01_NONCE[] = {
+    0xA0, 0x66, 0xFC, 0xC0, 0x9D, 0xD0, 0x1E, 0x6E,
+    0x2D, 0xF3, 0x26, 0x1A,
+};
+static const size_t TEST_MANUAL_01_NONCE_LEN = 12;
+static const size_t TEST_MANUAL_01_MAC_LEN = 8;
+static const uint8_t TEST_MANUAL_01_INPUT[] = {
+    /* AAD */
+    0x10, 0x25, 0x5F, 0xD5, 0xCE, 0x9C, 0xC6, 0xCD,
+    0x3B, 0x31, 0x21, 0xF5, 0x10, 0x26, 0x20, 0xFA,
+    0xE9, 0x7A, 0x52, 0x2D, 0x67, 0x4D, 0x8E, 0xD8,
+    0x4D, 0x0D, 0x85, 0x7C, 0xA3, 0xAD, 0x97, 0x28,
+    0xF9, 0x60, 0x8A, 0x8A, 0x67, 0x6D, 0xBC, 0x79,
+    /* PLAINTEXT */
+    0x6E, 0xA0, 0xA3, 0x0B, 0x80, 0x9A, 0x4A, 0x4E,
+    0xC1, 0x7F, 0xAB, 0x7E, 0x49, 0x64, 0x49, 0x7F,
+    0xA0, 0xE6, 0x70, 0x41, 0xDA, 0x16, 0x3D, 0x08,
+    0x70, 0x8E, 0xC4, 0x1B, 0xF1, 0x0E, 0xDA, 0xC8,
+    0xED, 0xA2, 0x35, 0xA2, 0xEE, 0x51, 0x62, 0x00,
+    0xEF, 0x8D, 0x5C, 0x5D, 0x83, 0xFA, 0xB6, 0xC8,
+    0xBC, 0xE4, 0x08, 0x78, 0xB6, 0x70, 0x0F, 0xE4,
+    0xC1, 0x70, 0x57, 0x31, 0x8D, 0x77, 0x43, 0x01,
+    0x55, 0x9E, 0x41, 0xAB, 0xE2, 0x6D, 0x37, 0x9A,
+    0x5B, 0x30, 0x25, 0xCC, 0xC4, 0x62, 0xCF, 0x91,
+    0x6B, 0xD2, 0x01, 0x7C, 0x05, 0xD7, 0x84, 0xAB,
+    0x0F, 0xB1, 0x2C, 0x73, 0x7B, 0xB0, 0x30, 0x44,
+    0xF5, 0x5E, 0x5D, 0x84, 0xF3, 0xB3, 0xBC, 0xFF,
+    0xCC, 0x44, 0x23, 0x29, 0xC0, 0xFA, 0x3C, 0xE3,
+    0x44, 0x64, 0x1E, 0x01, 0x8B, 0xD5, 0xBC, 0x8B,
+    0xCE, 0x6D, 0xB7, 0xC1, 0x5E, 0xDC, 0x99, 0x0F,
+    0x75, 0x01, 0xFE, 0xA4, 0x74, 0x0B, 0xE6, 0x37,
+    0xD5, 0x93, 0x58, 0x7B, 0x66, 0x53, 0x9F, 0x78,
+    0x89, 0xB9, 0x59, 0x9E, 0xB4, 0x55, 0xA5, 0x86,
+    0x03, 0x02, 0xDF, 0x8B, 0xB7, 0x8A, 0x02, 0xB7,
+    0x6E, 0x1D, 0xD2, 0xB0, 0x84, 0xB0, 0x02, 0xF8,
+    0x1C, 0xEA, 0x17, 0x4F, 0xF4, 0x22, 0x0C, 0xF4,
+    0x28, 0xFA, 0x8F, 0xA3, 0xE3, 0xDC, 0xB3, 0x9D,
+    0x53, 0xB9, 0x89, 0x59, 0x2D, 0x3A, 0xC7, 0xC7,
+    0x6D, 0xC9, 0x5E, 0x82, 0x3B, 0xFD, 0x90, 0x05,
+    0x5B, 0xFB, 0x51, 0xC1, 0x10, 0xE7, 0xF8, 0x82,
+    0x59, 0x23, 0x64, 0x96, 0x01, 0x6C, 0xD9, 0x64,
+    0xF9, 0xB9, 0xF2, 0x12, 0xBE, 0x30, 0x6C, 0x14,
+    0x76, 0x5A, 0x3C, 0xF1, 0x63, 0x71, 0x86, 0x8F,
+    0x29, 0x47, 0x8B, 0xB8, 0x6D, 0xA2, 0xE4, 0xF9,
+    0x29, 0x4E, 0x78, 0xD3, 0x66, 0xDC, 0xBA, 0xAD,
+    0x2B, 0xE0, 0xF7, 0x76, 0x08, 0xCF, 0x79, 0x2C,
+    0x5E, 0xC1, 0x9F, 0x67, 0x50, 0x2E, 0x96, 0x78,
+    0xBA, 0xD8, 0xC3, 0xD3, 0xEE, 0xEA,
+};
+static const size_t TEST_MANUAL_01_INPUT_LEN = 270;
+static const size_t TEST_MANUAL_01_ADATA_LEN = 40;
+static const uint8_t TEST_MANUAL_01_EXPECTED[] = {
+    /* AAD */
+    0x10, 0x25, 0x5F, 0xD5, 0xCE, 0x9C, 0xC6, 0xCD,
+    0x3B, 0x31, 0x21, 0xF5, 0x10, 0x26, 0x20, 0xFA,
+    0xE9, 0x7A, 0x52, 0x2D, 0x67, 0x4D, 0x8E, 0xD8,
+    0x4D, 0x0D, 0x85, 0x7C, 0xA3, 0xAD, 0x97, 0x28,
+    0xF9, 0x60, 0x8A, 0x8A, 0x67, 0x6D, 0xBC, 0x79,
+    /* CIPHERTEXT */
+    0x3B, 0x39, 0x41, 0x8A, 0xD8, 0xCF, 0x8D, 0xDD,
+    0xCD, 0x68, 0xE4, 0x61, 0xC5, 0x01, 0x1E, 0xD9,
+    0x16, 0x8A, 0xCC, 0x9C, 0xE8, 0x28, 0xBF, 0xC3,
+    0xBD, 0xF4, 0xFE, 0xFD, 0x4B, 0xDC, 0xC0, 0xAD,
+    0x56, 0xB5, 0x02, 0x65, 0x7D, 0x93, 0xA4, 0x00,
+    0x2A, 0x48, 0xD9, 0x4E, 0xC9, 0x2E, 0xF6, 0x30,
+    0x62, 0xBE, 0x50, 0x27, 0x81, 0x24, 0x5D, 0x04,
+    0xF5, 0x9B, 0x3C, 0x3C, 0xFB, 0xD1, 0x32, 0x67,
+    0x86, 0x5F, 0xDF, 0xD3, 0x1C, 0x53, 0xC8, 0x58,
+    0x86, 0xEA, 0xF5, 0x6A, 0x75, 0x43, 0x74, 0x3D,
+    0x15, 0x96, 0xB2, 0x54, 0x53, 0x28, 0xBC, 0xA2,
+    0x61, 0x9E, 0x5F, 0x68, 0xE4, 0xCD, 0x9E, 0x46,
+    0x6D, 0xDD, 0xA4, 0x82, 0x86, 0xFD, 0xD2, 0x67,
+    0x39, 0x2A, 0x71, 0x65, 0x7E, 0x5E, 0x0C, 0x8A,
+    0x64, 0xA2, 0xCD, 0x4A, 0x1F, 0x19, 0x49, 0xF4,
+    0xA7, 0xC5, 0x2B, 0x5D, 0xCC, 0xFD, 0x2F, 0xF4,
+    0xB5, 0x62, 0x20, 0xA4, 0xE4, 0x55, 0x03, 0xDE,
+    0x44, 0x7B, 0xD7, 0x2B, 0xD9, 0xAE, 0xED, 0x21,
+    0x3A, 0x16, 0xF4, 0x7E, 0xB3, 0xE1, 0xD1, 0x87,
+    0xD6, 0x89, 0xAA, 0x0C, 0x93, 0xCE, 0xEA, 0x0D,
+    0x9F, 0x24, 0xE2, 0xFD, 0x1D, 0x12, 0xF3, 0x5D,
+    0x7C, 0x95, 0xF4, 0x7A, 0xC5, 0x50, 0xD2, 0x04,
+    0xA4, 0x6F, 0xD0, 0xE8, 0xF0, 0x48, 0x01, 0xBC,
+    0xE1, 0x9E, 0x7A, 0xFB, 0xE2, 0xD8, 0xAB, 0xD8,
+    0xCD, 0x44, 0x7F, 0x3B, 0x16, 0xAE, 0xA5, 0xDF,
+    0xC4, 0x9A, 0xDF, 0xD5, 0xFF, 0xD2, 0x1F, 0xDA,
+    0x59, 0xEA, 0x71, 0x64, 0xCF, 0x55, 0x84, 0x90,
+    0xC2, 0x7E, 0xBD, 0x2C, 0x3A, 0xD2, 0x9F, 0x56,
+    0xC2, 0xE1, 0x25, 0x47, 0x31, 0x07, 0x8F, 0x53,
+    0xB7, 0x9A, 0xB7, 0x14, 0xA3, 0x81, 0x10, 0x97,
+    0xAB, 0x9B, 0x13, 0x7A, 0xAC, 0xED, 0xA9, 0x73,
+    0x10, 0x8F, 0xB3, 0xA3, 0x77, 0xBF, 0x3F, 0x9B,
+    0xB6, 0xB1, 0xAF, 0x07, 0xE5, 0xD1, 0x6E, 0x70,
+    0x66, 0x30, 0xAE, 0x4E, 0xFB, 0x56,
+    /* MAC */
+    0x2E, 0xB4, 0x86, 0xF7, 0x01, 0x6C, 0xD0, 0x6F
+
+};
+static const size_t TEST_MANUAL_01_EXPECTED_LEN = 318;
+
 /* Share test buffer output */
-static uint8_t data[60];
+static uint8_t data[512];
 
 static void test_encrypt_op(const uint8_t *key, uint8_t key_len,
                             const uint8_t *adata, size_t adata_len,
@@ -972,6 +1081,8 @@ static void test_crypto_modes_ccm_encrypt(void)
     do_test_encrypt_op(NIST_3);
 
     do_test_encrypt_op(WYCHEPROOF_28);
+
+    do_test_encrypt_op(MANUAL_01);
 }
 
 #define do_test_decrypt_op(name) do { \
@@ -1021,6 +1132,8 @@ static void test_crypto_modes_ccm_decrypt(void)
     do_test_decrypt_op(NIST_3);
 
     do_test_decrypt_op(WYCHEPROOF_28);
+
+    do_test_decrypt_op(MANUAL_01);
 }