diff --git a/README.md b/README.md
index 41f247f..53b14d5 100644
--- a/README.md
+++ b/README.md
@@ -15,15 +15,17 @@ Execute:
 The shared library uses NIF. Use the Erlang file `src/ecrecover.erl` to use this:
 
 ```
-c("src/ecrecover").
-c("src/ecrecover_util").
-Decoded = ecrecover_util:hex_to_bin("47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001b650acf9d3f5f0a2c799776a1254355d5f4061762a237396a99a0e0e3fc2bcd6729514a0dacb2e623ac4abd157cb18163ff942280db4d5caad66ddf941ba12e03").
-List = binary:bin_to_list(Decoded).
-Hash = binary:list_to_bin(lists:sublist(List, 1, 32)).
-Sig = binary:list_to_bin(lists:sublist(List, 64, 65)).
-Input = <<Hash/binary, 0:(8*31), Sig/binary>>.
-binary:bin_to_list(Input) == binary:bin_to_list(Decoded).
-Result = ecrecover:recover(Hash, Sig).
-Expected = ecrecover_util:hex_to_bin("000000000000000000000000c08b5542d177ac6686946920409741463a15dddb").
-binary:bin_to_list(Result) == binary:bin_to_list(Expected). %% check result
+./rebar3 shell
+Erlang/OTP 25 [erts-13.1.3] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [jit] [dtrace]
+Eshell V13.1.3  (abort with ^G)
+
+1> Decoded = binary:decode_hex(<<"47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001b650acf9d3f5f0a2c799776a1254355d5f4061762a237396a99a0e0e3fc2bcd6729514a0dacb2e623ac4abd157cb18163ff942280db4d5caad66ddf941ba12e03">>).
+2> List = binary:bin_to_list(Decoded).
+3> Hash = binary:list_to_bin(lists:sublist(List, 1, 32)).
+4> Sig = binary:list_to_bin(lists:sublist(List, 64, 65)).
+5> Input = <<Hash/binary, 0:(8*31), Sig/binary>>.
+6> binary:bin_to_list(Input) == binary:bin_to_list(Decoded).
+7> Result = ecrecover:recover(Hash, Sig).
+8> Expected = binary:decode_hex(<<"000000000000000000000000c08b5542d177ac6686946920409741463a15dddb">>).
+9> Result == Expected. %% check result
 ```
diff --git a/src/ecrecover_util.erl b/src/ecrecover_util.erl
deleted file mode 100644
index 6d154b7..0000000
--- a/src/ecrecover_util.erl
+++ /dev/null
@@ -1,28 +0,0 @@
--module(ecrecover_util).
-
--export([ recover_from_hex/1
-        , bin_to_hex/1
-        , hex_to_bin/1
-        ]).
-
-%%=============================================================================
-%% External API
-
-recover_from_hex(Input) ->
-    <<Hash:32/binary, _:31/binary, Sig:65/binary>> = hex_to_bin(Input),
-    PubKey = ecrecover:recover(Hash, Sig),
-    bin_to_hex(PubKey).
-
-bin_to_hex(Bin) ->
-    lists:flatten([io_lib:format("~2.16.0B", [X]) || X <- binary_to_list(Bin)]).
-
-hex_to_bin(S) ->
-    hex_to_bin(S, []).
-hex_to_bin([], Acc) ->
-    list_to_binary(lists:reverse(Acc));
-hex_to_bin([X,Y|T], Acc) ->
-    {ok, [V], []} = io_lib:fread("~16u", [X,Y]),
-    hex_to_bin(T, [V | Acc]);
-hex_to_bin([X|T], Acc) ->
-    {ok, [V], []} = io_lib:fread("~16u", lists:flatten([X,"0"])),
-    hex_to_bin(T, [V | Acc]).