diff --git a/c_src/aead.c b/c_src/aead.c
index fc4f0de..4339c99 100644
--- a/c_src/aead.c
+++ b/c_src/aead.c
@@ -41,13 +41,13 @@ enacl_crypto_aead_chacha20poly1305_encrypt(ErlNifEnv *env, int argc,
 
   if (argc != 4)
     goto bad_arg;
-  if (!enif_inspect_binary(env, argv[0], &key))
+  if (!enif_inspect_binary(env, argv[0], &message))
     goto bad_arg;
-  if (!enif_inspect_binary(env, argv[1], &nonce))
+  if (!enif_inspect_binary(env, argv[1], &ad))
     goto bad_arg;
-  if (!enif_inspect_binary(env, argv[2], &ad))
+  if (!enif_inspect_binary(env, argv[2], &nonce))
     goto bad_arg;
-  if (!enif_inspect_binary(env, argv[3], &message))
+  if (!enif_inspect_binary(env, argv[3], &key))
     goto bad_arg;
   if (key.size != crypto_aead_chacha20poly1305_ietf_KEYBYTES)
     goto bad_arg;
@@ -87,13 +87,13 @@ enacl_crypto_aead_chacha20poly1305_decrypt(ErlNifEnv *env, int argc,
 
   if (argc != 4)
     goto bad_arg;
-  if (!enif_inspect_binary(env, argv[0], &key))
+  if (!enif_inspect_binary(env, argv[0], &ciphertext))
     goto bad_arg;
-  if (!enif_inspect_binary(env, argv[1], &nonce))
+  if (!enif_inspect_binary(env, argv[1], &ad))
     goto bad_arg;
-  if (!enif_inspect_binary(env, argv[2], &ad))
+  if (!enif_inspect_binary(env, argv[2], &nonce))
     goto bad_arg;
-  if (!enif_inspect_binary(env, argv[3], &ciphertext))
+  if (!enif_inspect_binary(env, argv[3], &message))
     goto bad_arg;
 
   if (ciphertext.size < crypto_aead_chacha20poly1305_ietf_ABYTES)
diff --git a/src/enacl.erl b/src/enacl.erl
index 6cb0770..2a3d032 100644
--- a/src/enacl.erl
+++ b/src/enacl.erl
@@ -69,7 +69,7 @@
          aead_chacha20poly1305_encrypt/4,
          aead_chacha20poly1305_decrypt/4,
          aead_chacha20poly1305_KEYBYTES/0,
-         aead_chacha20poly1305_NONCEBYTES/0,
+         aead_chacha20poly1305_NPUBBYTES/0,
          aead_chacha20poly1305_ABYTES/0,
          aead_chacha20poly1305_MESSAGEBYTES_MAX/0,
 
@@ -1169,28 +1169,26 @@ kx_secret_key_size() ->
 %% `AD' using `Key' and `Nonce'. Returns the encrypted message followed by
 %% `aead_chacha20poly1305_ABYTES/0' bytes of MAC.
 %% @end
--spec aead_chacha20poly1305_encrypt(Key, Nonce, AD, Msg) -> binary() | {error, term()}
+-spec aead_chacha20poly1305_encrypt(Msg, AD, Nonce, Key) -> binary() | {error, term()}
     when Key :: binary(),
-         Nonce :: pos_integer(),
+         Nonce :: binary(),
          AD :: binary(),
          Msg :: binary().
-aead_chacha20poly1305_encrypt(Key, Nonce, AD, Msg) ->
-    NonceBin = <<0:32, Nonce:64/little-unsigned-integer>>,
-    enacl_nif:crypto_aead_chacha20poly1305_encrypt(Key, NonceBin, AD, Msg).
+aead_chacha20poly1305_encrypt(Msg, AD, Nonce, Key) ->
+    enacl_nif:crypto_aead_chacha20poly1305_encrypt(Msg, AD, Nonce, Key).
 
 %% @doc aead_chacha20poly1305_decrypt/4 decrypts ciphertext `CT' with additional
 %% data `AD' using `Key' and `Nonce'. Note: `CipherText' should contain
 %% `aead_chacha20poly1305_ABYTES/0' bytes that is the MAC. Returns the decrypted
 %% message.
 %% @end
--spec aead_chacha20poly1305_decrypt(Key, Nonce, AD, CT) -> binary() | {error, term()}
+-spec aead_chacha20poly1305_decrypt(CT, AD, Nonce, Key) -> binary() | {error, term()}
     when Key :: binary(),
-         Nonce :: pos_integer(),
+         Nonce :: binary(),
          AD :: binary(),
          CT :: binary().
-aead_chacha20poly1305_decrypt(Key, Nonce, AD, CT) ->
-    NonceBin = <<0:32, Nonce:64/little-unsigned-integer>>,
-    enacl_nif:crypto_aead_chacha20poly1305_decrypt(Key, NonceBin, AD, CT).
+aead_chacha20poly1305_decrypt(CT, AD, Nonce, Key) ->
+    enacl_nif:crypto_aead_chacha20poly1305_decrypt(CT, AD, Nonce, Key).
 
 %% @doc aead_chacha20poly1305_KEYBYTES/0 returns the number of bytes
 %% of the key used in AEAD ChaCha20 Poly1305 encryption/decryption.
@@ -1199,11 +1197,11 @@ aead_chacha20poly1305_decrypt(Key, Nonce, AD, CT) ->
 aead_chacha20poly1305_KEYBYTES() ->
     enacl_nif:crypto_aead_chacha20poly1305_KEYBYTES().
 
-%% @doc aead_chacha20poly1305_NONCEBYTES/0 returns the number of bytes
+%% @doc aead_chacha20poly1305_NPUBBYTES/0 returns the number of bytes
 %% of the Nonce in AEAD ChaCha20 Poly1305 encryption/decryption.
 %% @end
--spec aead_chacha20poly1305_NONCEBYTES() -> pos_integer().
-aead_chacha20poly1305_NONCEBYTES() ->
+-spec aead_chacha20poly1305_NPUBBYTES() -> pos_integer().
+aead_chacha20poly1305_NPUBBYTES() ->
     enacl_nif:crypto_aead_chacha20poly1305_NPUBBYTES().
 
 %% @doc aead_chacha20poly1305_ABYTES/0 returns the number of bytes
diff --git a/src/enacl_nif.erl b/src/enacl_nif.erl
index a6d6ec5..dfa7b97 100644
--- a/src/enacl_nif.erl
+++ b/src/enacl_nif.erl
@@ -272,15 +272,15 @@ crypto_stream_b(_Bytes, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
 crypto_stream_xor(_M, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
 crypto_stream_xor_b(_M, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
 
-crypto_aead_chacha20poly1305_encrypt(_Key, _Nonce, _AD, _Message) -> erlang:nif_error(nif_not_loaded).
-crypto_aead_chacha20poly1305_decrypt(_Key, _Nonce, _AD, _Message) -> erlang:nif_error(nif_not_loaded).
+crypto_aead_chacha20poly1305_encrypt(_Message, _AD, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
+crypto_aead_chacha20poly1305_decrypt(_CipherText, _AD, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
 crypto_aead_chacha20poly1305_KEYBYTES()                           -> erlang:nif_error(nif_not_loaded).
 crypto_aead_chacha20poly1305_NPUBBYTES()                          -> erlang:nif_error(nif_not_loaded).
 crypto_aead_chacha20poly1305_ABYTES()                             -> erlang:nif_error(nif_not_loaded).
 crypto_aead_chacha20poly1305_MESSAGEBYTES_MAX()                   -> erlang:nif_error(nif_not_loaded).
 
-crypto_aead_xchacha20poly1305_encrypt(_Key, _Nonce, _AD, _Message) -> erlang:nif_error(nif_not_loaded).
-crypto_aead_xchacha20poly1305_decrypt(_Key, _Nonce, _AD, _Message) -> erlang:nif_error(nif_not_loaded).
+crypto_aead_xchacha20poly1305_encrypt(_Message, _AD, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
+crypto_aead_xchacha20poly1305_decrypt(_CipherText, _AD, _Nonce, _Key) -> erlang:nif_error(nif_not_loaded).
 crypto_aead_xchacha20poly1305_KEYBYTES()                           -> erlang:nif_error(nif_not_loaded).
 crypto_aead_xchacha20poly1305_NPUBBYTES()                          -> erlang:nif_error(nif_not_loaded).
 crypto_aead_xchacha20poly1305_ABYTES()                             -> erlang:nif_error(nif_not_loaded).
diff --git a/test/enacl_SUITE.erl b/test/enacl_SUITE.erl
index 8ff5b5c..b752bba 100644
--- a/test/enacl_SUITE.erl
+++ b/test/enacl_SUITE.erl
@@ -103,14 +103,15 @@ aead_xchacha20poly1305(_Config) ->
     ok.
 
 aead_chacha20poly1305(_Config) ->
+    NonceLen = enacl:aead_chacha20poly1305_NPUBBYTES(),
     KLen = enacl:aead_chacha20poly1305_KEYBYTES(),
     Key = binary:copy(<<"K">>, KLen),
     Msg = <<"test">>,
     AD = <<1,2,3,4,5,6>>,
-    Nonce = 1337,
+    Nonce = binary:copy(<<"N">>, NonceLen),
 
-    CipherText = enacl:aead_chacha20poly1305_encrypt(Key, Nonce, AD, Msg),
-    Msg = enacl:aead_chacha20poly1305_decrypt(Key, Nonce, AD, CipherText),
+    CipherText = enacl:aead_chacha20poly1305_encrypt(Msg, AD, Nonce, Key),
+    Msg = enacl:aead_chacha20poly1305_decrypt(CipherText, AD, Nonce, Key),
     ok.
 
 pwhash(_Config) ->