diff --git a/lib/cose/cwt.ex b/lib/cose/cwt.ex
index 0e93693..ecc0d21 100644
--- a/lib/cose/cwt.ex
+++ b/lib/cose/cwt.ex
@@ -87,7 +87,7 @@ defmodule COSE.CWT do
   end
 
   def peek_claims(token, custom_claims \\ %{}) do
-    msg = Sign1.decode(token)
+    {:ok, msg} = Sign1.decode_cbor(token)
     {:ok, cbor_claims, ""} = CBOR.decode(msg.payload.value)
 
     cbor_claims
diff --git a/lib/cose/keys/ecc.ex b/lib/cose/keys/ecc.ex
index 6a8240f..fc67891 100644
--- a/lib/cose/keys/ecc.ex
+++ b/lib/cose/keys/ecc.ex
@@ -18,7 +18,7 @@ defmodule COSE.Keys.ECC do
     {curve, cose_crv, key_len} = get_curve_info(alg)
     {pub, priv} = :crypto.generate_key(:ecdh, curve)
 
-    <<4, x::binary-size(key_len), y::binary-size(key_len)>> = pub
+    <<4, x::binary-size(^key_len), y::binary-size(^key_len)>> = pub
 
     %__MODULE__{
       kty: :ecc,
@@ -70,7 +70,7 @@ defmodule COSE.Keys.ECC do
       end
 
     case final_pub do
-      <<4, x::binary-size(key_len), y::binary-size(key_len)>> ->
+      <<4, x::binary-size(^key_len), y::binary-size(^key_len)>> ->
         %__MODULE__{
           kty: :ecc,
           crv: cose_crv,
@@ -128,7 +128,7 @@ defmodule COSE.Keys.ECC do
 
   defp bitstring_to_binary(val) when is_bitstring(val) do
     size = bit_size(val)
-    <<bin::binary-size(div(size, 8)), _::bitstring>> = val
+    <<bin::binary-size(div(^size, 8)), _::bitstring>> = val
 
     bin
   end
@@ -183,7 +183,7 @@ defimpl COSE.Keys.Key, for: COSE.Keys.ECC do
 
   def raw_to_der(raw_sig, key_size) do
     case raw_sig do
-      <<r::binary-size(key_size), s::binary-size(key_size)>> ->
+      <<r::binary-size(^key_size), s::binary-size(^key_size)>> ->
         (encode_integer(r) <> encode_integer(s))
         |> wrap_sequence()
         |> then(&{:ok, &1})
diff --git a/lib/cose/keys/keys.ex b/lib/cose/keys/keys.ex
index a72ad17..7156fc8 100644
--- a/lib/cose/keys/keys.ex
+++ b/lib/cose/keys/keys.ex
@@ -11,7 +11,6 @@ defmodule COSE.Keys do
   alias COSE.Keys.RSA
 
   @oid_rsa {1, 2, 840, 113_549, 1, 1, 1}
-  @oid_ec {1, 2, 840, 10045, 2, 1}
 
   def sign(key, digest_type, to_be_signed), do: Key.sign(key, digest_type, to_be_signed)
 
@@ -68,9 +67,6 @@ defmodule COSE.Keys do
       {:ECPrivateKey, _, _, _, _, _} ->
         {:ok, ECC.from_record(pem_record)}
 
-      {:PrivateKeyInfo, _, {_, @oid_ec, _}, _, _} ->
-        {:ok, ECC.from_record(pem_record)}
-
       _ ->
         false
     end
diff --git a/lib/cose/messages/encrypt.ex b/lib/cose/messages/encrypt.ex
index 7982f85..44d7e89 100644
--- a/lib/cose/messages/encrypt.ex
+++ b/lib/cose/messages/encrypt.ex
@@ -98,7 +98,7 @@ defmodule COSE.Messages.Encrypt do
 
   def split_encrypted_tag(ciphertext, tag_len \\ 8) do
     encrypted_len = byte_size(ciphertext) - tag_len
-    <<encrypted::binary-size(encrypted_len), tag::binary-size(tag_len)>> = ciphertext
+    <<encrypted::binary-size(^encrypted_len), tag::binary-size(^tag_len)>> = ciphertext
     {encrypted, tag}
   end
 end
diff --git a/lib/cose/messages/encrypt0.ex b/lib/cose/messages/encrypt0.ex
index cb2d731..bcbe95d 100644
--- a/lib/cose/messages/encrypt0.ex
+++ b/lib/cose/messages/encrypt0.ex
@@ -93,7 +93,7 @@ defmodule COSE.Messages.Encrypt0 do
 
   def split_encrypted_tag(ciphertext, tag_len \\ 16) do
     encrypted_len = byte_size(ciphertext) - tag_len
-    <<encrypted::binary-size(encrypted_len), tag::binary-size(tag_len)>> = ciphertext
+    <<encrypted::binary-size(^encrypted_len), tag::binary-size(^tag_len)>> = ciphertext
     {encrypted, tag}
   end
 end
diff --git a/test/cwt_test.exs b/test/cwt_test.exs
index f52b637..3670ade 100644
--- a/test/cwt_test.exs
+++ b/test/cwt_test.exs
@@ -59,5 +59,12 @@ defmodule COSETest.CWT do
       retrived_claims = cwt |> Map.delete(:issued_at)
       assert ^claims = retrived_claims
     end
+
+    test "peek claims without verifying the signature", %{key: key, claims: claims} do
+      {:ok, token} = CWT.sign_encode_cbor(claims, key)
+
+      retrived_claims = CWT.peek_claims(token) |> Map.delete(:issued_at)
+      assert ^claims = retrived_claims
+    end
   end
 end