diff --git a/src/jsx_decoder.erl b/src/jsx_decoder.erl
index 3a47205..afb278c 100644
--- a/src/jsx_decoder.erl
+++ b/src/jsx_decoder.erl
@@ -120,12 +120,12 @@ decoder(Opts) ->
 ).
 -endif.
 
--define(new_seq(), []).
--define(new_seq(C), [C]).
+-define(new_seq(), <<>>).
+-define(new_seq(C), <<C/utf8>>).
 
--define(acc_seq(Seq, C), [C] ++ Seq).
+-define(acc_seq(Seq, C), <<Seq/binary, C/utf8>>).
 
--define(end_seq(Seq), lists:reverse(Seq)).
+-define(end_seq(Seq), Seq).
 
 
 start(<<?start_object, Rest/binary>>, Out, Stack, Opts) ->
@@ -141,11 +141,11 @@ start(<<$f, Rest/binary>>, Out, Stack, Opts) ->
 start(<<$n, Rest/binary>>, Out, Stack, Opts) ->
     nu(Rest, Out, Stack, Opts);
 start(<<?negative, Rest/binary>>, Out, Stack, Opts) ->
-    negative(Rest, Out, [?new_seq($-)|Stack], Opts);
+    negative(Rest, Out, [[$-]|Stack], Opts);
 start(<<?zero, Rest/binary>>, Out, Stack, Opts) ->
-    zero(Rest, Out, [?new_seq($0)|Stack], Opts);
+    zero(Rest, Out, [[$0]|Stack], Opts);
 start(<<S/utf8, Rest/binary>>, Out, Stack, Opts) when ?is_nonzero(S) ->
-    integer(Rest, Out, [?new_seq(S)|Stack], Opts);
+    integer(Rest, Out, [[S]|Stack], Opts);
 start(<<S, Rest/binary>>, Out, Stack, Opts) when ?is_whitespace(S) -> 
     start(Rest, Out, Stack, Opts);
 start(<<>>, Out, Stack, Opts) ->
@@ -175,11 +175,11 @@ array(<<$f, Rest/binary>>, Out, Stack, Opts) ->
 array(<<$n, Rest/binary>>, Out, Stack, Opts) ->
     nu(Rest, Out, Stack, Opts);
 array(<<?negative, Rest/binary>>, Out, Stack, Opts) ->
-    negative(Rest, Out, [?new_seq($-)|Stack], Opts);
+    negative(Rest, Out, [[$-]|Stack], Opts);
 array(<<?zero, Rest/binary>>, Out, Stack, Opts) ->
-    zero(Rest, Out, [?new_seq($0)|Stack], Opts);
+    zero(Rest, Out, [[$0]|Stack], Opts);
 array(<<S, Rest/binary>>, Out, Stack, Opts) when ?is_nonzero(S) ->
-    integer(Rest, Out, [?new_seq(S)|Stack], Opts);
+    integer(Rest, Out, [[S]|Stack], Opts);
 array(<<?start_object, Rest/binary>>, Out, Stack, Opts) ->
     ?event([start_object], object, Rest, Out, [key|Stack], Opts);
 array(<<?start_array, Rest/binary>>, Out, Stack, Opts) ->
@@ -203,11 +203,11 @@ value(<<$f, Rest/binary>>, Out, Stack, Opts) ->
 value(<<$n, Rest/binary>>, Out, Stack, Opts) ->
     nu(Rest, Out, Stack, Opts);
 value(<<?negative, Rest/binary>>, Out, Stack, Opts) ->
-    negative(Rest, Out, [?new_seq($-)|Stack], Opts);
+    negative(Rest, Out, [[$-]|Stack], Opts);
 value(<<?zero, Rest/binary>>, Out, Stack, Opts) ->
-    zero(Rest, Out, [?new_seq($0)|Stack], Opts);
+    zero(Rest, Out, [[$0]|Stack], Opts);
 value(<<S, Rest/binary>>, Out, Stack, Opts) when ?is_nonzero(S) ->
-    integer(Rest, Out, [?new_seq(S)|Stack], Opts);
+    integer(Rest, Out, [[S]|Stack], Opts);
 value(<<?start_object, Rest/binary>>, Out, Stack, Opts) ->
     ?event([start_object], object, Rest, Out, [key|Stack], Opts);
 value(<<?start_array, Rest/binary>>, Out, Stack, Opts) ->
@@ -335,7 +335,7 @@ escape(<<$r, Rest/binary>>, Out, [Acc|Stack], Opts) ->
 escape(<<$t, Rest/binary>>, Out, [Acc|Stack], Opts) ->
     string(Rest, Out, [?acc_seq(Acc, $\t)|Stack], Opts);
 escape(<<$u, Rest/binary>>, Out, Stack, Opts) ->
-    escaped_unicode(Rest, Out, [?new_seq()|Stack], Opts);      
+    escaped_unicode(Rest, Out, [[]|Stack], Opts);      
 escape(<<S, Rest/binary>>, Out, [Acc|Stack], Opts) 
         when S =:= ?quote; S =:= ?solidus; S =:= ?rsolidus ->
     string(Rest, Out, [?acc_seq(Acc, S)|Stack], Opts);
@@ -376,7 +376,7 @@ escaped_unicode(<<D, Rest/binary>>, Out, [[C,B,A], Acc|Stack], Opts)
     end;
 escaped_unicode(<<S, Rest/binary>>, Out, [Acc|Stack], Opts) 
         when ?is_hex(S) ->
-    escaped_unicode(Rest, Out, [?acc_seq(Acc, S)|Stack], Opts);
+    escaped_unicode(Rest, Out, [[S] ++ Acc|Stack], Opts);
 escaped_unicode(<<>>, Out, Stack, Opts) ->
     ?incomplete(escaped_unicode, <<>>, Out, Stack, Opts);
 escaped_unicode(Bin, Out, Stack, Opts) ->
@@ -401,7 +401,7 @@ low_surrogate(Bin, Out, Stack, Opts) ->
 
 
 low_surrogate_u(<<$u, Rest/binary>>, Out, Stack, Opts) ->
-    low_surrogate_v(Rest, Out, [?new_seq()|Stack], Opts);
+    low_surrogate_v(Rest, Out, [[]|Stack], Opts);
 low_surrogate_u(<<>>, Out, Stack, Opts) ->
     ?incomplete(low_surrogate_u, <<>>, Out, Stack, Opts);
 %% not a low surrogate, dispatch back to string to handle, including the
@@ -441,7 +441,7 @@ low_surrogate_v(<<D, Rest/binary>>, Out, [[C,B,A], High, String|Stack], Opts)
     end;
 low_surrogate_v(<<S, Rest/binary>>, Out, [Acc|Stack], Opts) 
         when ?is_hex(S) ->
-    low_surrogate_v(Rest, Out, [?acc_seq(Acc, S)|Stack], Opts);
+    low_surrogate_v(Rest, Out, [[S] ++ Acc|Stack], Opts);
 low_surrogate_v(<<>>, Out, Stack, Opts) ->
     ?incomplete(low_surrogate_v, <<>>, Out, Stack, Opts);
 low_surrogate_v(Bin, Out, Stack, Opts) ->
@@ -783,7 +783,7 @@ check_bad(List) ->
     ).
 
 check_replaced(List) ->
-    lists:dropwhile(fun({_, [{string, [16#fffd]}|_]}) ->
+    lists:dropwhile(fun({_, [{string, <<16#fffd/utf8>>}|_]}) ->
                 true
             ; (_) -> 
                 false 
diff --git a/src/jsx_encoder.erl b/src/jsx_encoder.erl
index 5d0d373..7c2e020 100644
--- a/src/jsx_encoder.erl
+++ b/src/jsx_encoder.erl
@@ -61,26 +61,15 @@ encoder(OptsList) ->
 
 
 
-start([{string, String}], [], [], Opts) when is_binary(String); is_list(String) ->
-    {ok,
-        [{string,
-            unicode:characters_to_list(jsx_utils:json_escape(String, Opts))},
-            end_json
-        ]
-    };
+start([{string, String}], [], [], Opts) when is_binary(String) ->
+    {ok, [{string, jsx_utils:json_escape(String, Opts)}, end_json]};
 start([{float, Float}], [], [], _Opts) when is_float(Float) ->
-    {ok,
-        [{float, Float}, end_json]
-    };
+    {ok, [{float, Float}, end_json]};
 start([{integer, Int}], [], [], _Opts) when is_integer(Int) ->
-    {ok,
-        [{integer, Int}, end_json]
-    };
+    {ok, [{integer, Int}, end_json]};
 start([{literal, Atom}], [], [], _Opts)
         when Atom == true; Atom == false; Atom == null ->
-    {ok,
-        [{literal, Atom}, end_json]
-    };
+    {ok, [{literal, Atom}, end_json]};
 %% third parameter is a stack to match end_foos to start_foos
 start(Forms, [], [], Opts) when is_list(Forms) ->
     list_or_object(Forms, [], [], Opts);
@@ -96,9 +85,9 @@ list_or_object([], T, Stack, Opts) ->
 list_or_object(Forms, T, Stack, Opts) -> ?error([Forms, T, Stack, Opts]).
 
  
-key([{key, Key}|Forms], T, Stack, Opts) when is_binary(Key); is_list(Key) ->
+key([{key, Key}|Forms], T, Stack, Opts) when is_binary(Key) ->
     ?event([{key,
-            unicode:characters_to_list(jsx_utils:json_escape(Key, Opts))
+            unicode:characters_to_binary(jsx_utils:json_escape(Key, Opts))
         }],
         value, Forms, T, Stack, Opts
     );
@@ -108,8 +97,8 @@ key([], T, Stack, Opts) -> ?incomplete(key, T, Stack, Opts);
 key(Forms, T, Stack, Opts) -> ?error([Forms, T, Stack, Opts]).
 
 
-value([{string, S}|Forms], T, Stack, Opts) when is_binary(S); is_list(S) ->
-    ?event([{string, unicode:characters_to_list(jsx_utils:json_escape(S, Opts))}],
+value([{string, S}|Forms], T, Stack, Opts) when is_binary(S) ->
+    ?event([{string, jsx_utils:json_escape(S, Opts)}],
         maybe_done, Forms, T, Stack, Opts
     );
 value([{float, F}|Forms], T, Stack, Opts) when is_float(F) ->
@@ -141,8 +130,7 @@ maybe_done([], T, Stack, Opts) -> ?incomplete(maybe_done, T, Stack, Opts);
 maybe_done(Forms, T, Stack, Opts) -> ?error([Forms, T, Stack, Opts]).
 
 
-done([], T, [], _Opts) ->
-    {ok, lists:reverse(T)};
+done([], T, [], _Opts) -> {ok, lists:reverse(T)};
 done(Forms, T, Stack, Opts) -> ?error([Forms, T, Stack, Opts]).
 
 
@@ -164,9 +152,9 @@ encode_test_() ->
         {"empty object", ?_assert(encode([start_object, end_object, end_json]))},
         {"empty array", ?_assert(encode([start_array, end_array, end_json]))},
         {"nested empty objects", ?_assert(encode([start_object,
-            {key, "empty object"},
+            {key, <<"empty object">>},
             start_object,
-            {key, "empty object"},
+            {key, <<"empty object">>},
             start_object,
             end_object,
             end_object,
@@ -182,19 +170,19 @@ encode_test_() ->
             end_json
         ]))},
         {"simple object", ?_assert(encode([start_object, 
-            {key, "a"},
-            {string, "hello"},
-            {key, "b"},
+            {key, <<"a">>},
+            {string, <<"hello">>},
+            {key, <<"b">>},
             {integer, 1},
-            {key, "c"},
+            {key, <<"c">>},
             {float, 1.0},
-            {key, "d"},
+            {key, <<"d">>},
             {literal, true},
             end_object,
             end_json
         ]))},
         {"simple array", ?_assert(encode([start_array,
-            {string, "hello"},
+            {string, <<"hello">>},
             {integer, 1},
             {float, 1.0},
             {literal, true},
@@ -207,8 +195,8 @@ encode_test_() ->
             end_array,
             end_json
         ]))},
-        {"naked string", ?_assert((jsx:scanner())([{string, "hello"}])
-            =:= {ok, [{string, "hello"}, end_json]}
+        {"naked string", ?_assert((jsx:scanner())([{string, <<"hello">>}])
+            =:= {ok, [{string, <<"hello">>}, end_json]}
         )},
         {"naked literal", ?_assert((jsx:scanner())([{literal, true}])
             =:= {ok, [{literal, true}, end_json]}
diff --git a/test/cases/array.test b/test/cases/array.test
index f1c235f..7150207 100644
--- a/test/cases/array.test
+++ b/test/cases/array.test
@@ -1,8 +1,8 @@
 {name, "array"}.
 {jsx, [start_array,
- {string,"foo"},
- {string,"bar"},
- {string,"baz"},
+ {string,<<"foo">>},
+ {string,<<"bar">>},
+ {string,<<"baz">>},
  start_array,
  {literal,true},
  end_array,start_array,
@@ -15,14 +15,14 @@
  {literal,null},
  {float,0.7},
  start_object,
- {key,"key"},
- {string,"value"},
+ {key,<<"key">>},
+ {string,<<"value">>},
  end_object,start_array,start_object,end_object,
  {literal,null},
  {literal,null},
  {literal,null},
  start_array,end_array,end_array,
- {string,"\n\r\\"},
+ {string,<<"\n\r\\">>},
  start_array,
  {integer,-1},
  end_array,end_array,end_json]}.
diff --git a/test/cases/bad_low_surrogate_replaced.test b/test/cases/bad_low_surrogate_replaced.test
index 2fc7b3d..7f13f9e 100644
--- a/test/cases/bad_low_surrogate_replaced.test
+++ b/test/cases/bad_low_surrogate_replaced.test
@@ -1,4 +1,4 @@
 {name, "bad_low_surrogate_replaced"}.
-{jsx, [start_array,{string, [16#fffd, 16#fffd]},end_array,end_json]}.
+{jsx, [start_array,{string, <<16#fffd/utf8, 16#fffd/utf8>>},end_array,end_json]}.
 {json, "bad_low_surrogate_replaced.json"}.
 {jsx_flags, [loose_unicode]}.
diff --git a/test/cases/encoded_surrogates.test b/test/cases/encoded_surrogates.test
index ae071c7..aa5d317 100644
--- a/test/cases/encoded_surrogates.test
+++ b/test/cases/encoded_surrogates.test
@@ -1,3 +1,3 @@
 {name, "encoded_surrogates"}.
-{jsx, [start_array,{string,[66560]},end_array,end_json]}.
+{jsx, [start_array,{string,<<66560/utf8>>},end_array,end_json]}.
 {json, "encoded_surrogates.json"}.
diff --git a/test/cases/escaped_noncharacter_ext_replaced.test b/test/cases/escaped_noncharacter_ext_replaced.test
index 413116e..0a740b6 100644
--- a/test/cases/escaped_noncharacter_ext_replaced.test
+++ b/test/cases/escaped_noncharacter_ext_replaced.test
@@ -1,4 +1,4 @@
 {name, "escaped noncharacter (extended)"}.
-{jsx, [{string, [16#fffd]}, end_json]}.
+{jsx, [{string, <<16#fffd/utf8>>}, end_json]}.
 {json, "escaped_noncharacter_ext.json"}.
 {jsx_flags, [loose_unicode]}.
\ No newline at end of file
diff --git a/test/cases/escaped_noncharacter_replaced.test b/test/cases/escaped_noncharacter_replaced.test
index 1cb374e..9c5faac 100644
--- a/test/cases/escaped_noncharacter_replaced.test
+++ b/test/cases/escaped_noncharacter_replaced.test
@@ -1,4 +1,4 @@
 {name, "escaped noncharacter replacement"}.
-{jsx, [{string,[16#fffd]},end_json]}.
+{jsx, [{string,<<16#fffd/utf8>>},end_json]}.
 {json, "escaped_noncharacter_replaced.json"}.
 {jsx_flags, [loose_unicode]}.
\ No newline at end of file
diff --git a/test/cases/escaped_nullbyte_replaced.test b/test/cases/escaped_nullbyte_replaced.test
index 289bb01..785acc8 100644
--- a/test/cases/escaped_nullbyte_replaced.test
+++ b/test/cases/escaped_nullbyte_replaced.test
@@ -1,4 +1,4 @@
 {name, "escaped nullbyte replaced"}.
-{jsx, [{string,[16#fffd]},end_json]}.
+{jsx, [{string,<<16#fffd/utf8>>},end_json]}.
 {json, "escaped_nullbyte_replaced.json"}.
 {jsx_flags, [loose_unicode]}.
\ No newline at end of file
diff --git a/test/cases/exp.test b/test/cases/exp.test
index 02d4416..c4b9bd4 100644
--- a/test/cases/exp.test
+++ b/test/cases/exp.test
@@ -4,9 +4,9 @@
  end_array,
  {float,2.0e7},
  start_object,
- {key,"key"},
+ {key,<<"key">>},
  {float,2.0e7},
- {key,"another key"},
+ {key,<<"another key">>},
  {float,2.0e7},
  end_object,
  {float,4.2e70},
diff --git a/test/cases/fraction.test b/test/cases/fraction.test
index 1b0d791..7cfdcf2 100644
--- a/test/cases/fraction.test
+++ b/test/cases/fraction.test
@@ -4,14 +4,14 @@
  end_array,
  {float,2.0},
  start_object,
- {key,"key"},
+ {key,<<"key">>},
  {float,2.0e7},
- {key,"another key"},
+ {key,<<"another key">>},
  {float,2.0e7},
  end_object,start_object,
- {key,"key"},
+ {key,<<"key">>},
  {float,2.0},
- {key,"another key"},
+ {key,<<"another key">>},
  {float,2.0},
  end_object,
  {float,4.321},
diff --git a/test/cases/integer.test b/test/cases/integer.test
index 2f2eee9..0883c33 100644
--- a/test/cases/integer.test
+++ b/test/cases/integer.test
@@ -4,9 +4,9 @@
  end_array,
  {integer,20},
  start_object,
- {key,"key"},
+ {key,<<"key">>},
  {integer,20},
- {key,"another key"},
+ {key,<<"another key">>},
  {integer,20},
  end_object,
  {integer,42},
diff --git a/test/cases/multibyte_utf.test b/test/cases/multibyte_utf.test
index 6a9217e..cb8be9c 100644
--- a/test/cases/multibyte_utf.test
+++ b/test/cases/multibyte_utf.test
@@ -1,3 +1,3 @@
 {name, "multibyte_utf"}.
-{jsx, [start_array,{string,[32,119070,32]},end_array,end_json]}.
+{jsx, [start_array,{string,<<32,119070/utf8,32>>},end_array,end_json]}.
 {json, "multibyte_utf.json"}.
diff --git a/test/cases/naked_string.test b/test/cases/naked_string.test
index 3ce5c36..68fe34b 100644
--- a/test/cases/naked_string.test
+++ b/test/cases/naked_string.test
@@ -1,3 +1,3 @@
 {name, "naked_string"}.
-{jsx, [{string,"this is a naked string"},end_json]}.
+{jsx, [{string,<<"this is a naked string">>},end_json]}.
 {json, "naked_string.json"}.
diff --git a/test/cases/negative_zero.test b/test/cases/negative_zero.test
index 0ef4f1a..0bc734a 100644
--- a/test/cases/negative_zero.test
+++ b/test/cases/negative_zero.test
@@ -4,9 +4,9 @@
  end_array,
  {integer,0},
  start_object,
- {key,"key"},
+ {key,<<"key">>},
  {integer,0},
- {key,"another key"},
+ {key,<<"another key">>},
  {integer,0},
  end_object,
  {integer,0},
diff --git a/test/cases/noncharacter_replaced.test b/test/cases/noncharacter_replaced.test
index 2e1752c..0944886 100644
--- a/test/cases/noncharacter_replaced.test
+++ b/test/cases/noncharacter_replaced.test
@@ -1,4 +1,4 @@
 {name, "noncharacter replaced"}.
-{jsx, [{string,[16#fffd]},end_json]}.
+{jsx, [{string,<<16#fffd/utf8>>},end_json]}.
 {json, "noncharacter_replaced.json"}.
 {jsx_flags, [loose_unicode]}.
\ No newline at end of file
diff --git a/test/cases/nullbyte_replaced.test b/test/cases/nullbyte_replaced.test
index 9a3ab0f..9a909eb 100644
--- a/test/cases/nullbyte_replaced.test
+++ b/test/cases/nullbyte_replaced.test
@@ -1,4 +1,4 @@
 {name, "nullbyte replaced"}.
-{jsx, [{string,[16#fffd]},end_json]}.
+{jsx, [{string,<<16#fffd/utf8>>},end_json]}.
 {json, "nullbyte_replaced.json"}.
 {jsx_flags, [loose_unicode]}.
\ No newline at end of file
diff --git a/test/cases/object.test b/test/cases/object.test
index b9b50d4..4877fc8 100644
--- a/test/cases/object.test
+++ b/test/cases/object.test
@@ -1,22 +1,22 @@
 {name, "object"}.
 {jsx, [start_object,
- {key,"foo"},
- {string,"bar"},
- {key,"baz"},
+ {key,<<"foo">>},
+ {string,<<"bar">>},
+ {key,<<"baz">>},
  {literal,true},
- {key,"false"},
+ {key,<<"false">>},
  {literal,null},
- {key,"object"},
+ {key,<<"object">>},
  start_object,
- {key,"key"},
- {string,"value"},
+ {key,<<"key">>},
+ {string,<<"value">>},
  end_object,
- {key,"list"},
+ {key,<<"list">>},
  start_array,
  {literal,null},
  {literal,null},
  {literal,null},
  start_array,end_array,
- {string,"\n\r\\"},
+ {string,<<"\n\r\\">>},
  end_array,end_object,end_json]}.
 {json, "object.json"}.
diff --git a/test/cases/string.test b/test/cases/string.test
index 8df9aa5..e1334d3 100644
--- a/test/cases/string.test
+++ b/test/cases/string.test
@@ -1,5 +1,5 @@
 {name, "string"}.
 {jsx, [start_array,
- {string,"this is a random string with \n embedded escapes in it"},
+ {string,<<"this is a random string with \n embedded escapes in it">>},
  end_array,end_json]}.
 {json, "string.json"}.
diff --git a/test/cases/string_escapes.test b/test/cases/string_escapes.test
index e33a903..7cd460c 100644
--- a/test/cases/string_escapes.test
+++ b/test/cases/string_escapes.test
@@ -1,12 +1,12 @@
 {name, "string_escapes"}.
 {jsx, [start_array,
- {string,"\""},
- {string,"\\"},
- {string,"/"},
- {string,"\b"},
- {string,"\f"},
- {string,"\n"},
- {string,"\r"},
- {string,"\t"},
+ {string,<<"\"">>},
+ {string,<<"\\">>},
+ {string,<<"/">>},
+ {string,<<"\b">>},
+ {string,<<"\f">>},
+ {string,<<"\n">>},
+ {string,<<"\r">>},
+ {string,<<"\t">>},
  end_array,end_json]}.
 {json, "string_escapes.json"}.
diff --git a/test/cases/unicode_to_codepoint.test b/test/cases/unicode_to_codepoint.test
index 587220c..71f47fd 100644
--- a/test/cases/unicode_to_codepoint.test
+++ b/test/cases/unicode_to_codepoint.test
@@ -1,6 +1,6 @@
 {name, "unicode_to_codepoint"}.
 {jsx, [start_array,
- {string,"arabic letter alef: "},
- {string,[1575]},
+ {string,<<"arabic letter alef: ">>},
+ {string,<<1575/utf8>>},
  end_array,end_json]}.
 {json, "unicode_to_codepoint.json"}.
diff --git a/test/cases/unpaired_surrogate_replaced.test b/test/cases/unpaired_surrogate_replaced.test
index 5061dc8..7d3bbbd 100644
--- a/test/cases/unpaired_surrogate_replaced.test
+++ b/test/cases/unpaired_surrogate_replaced.test
@@ -1,4 +1,4 @@
 {name, "unpaired surrogate replaced"}.
-{jsx, [start_array,{string,[65533,$b,$l,$a,$h]},end_array,end_json]}.
+{jsx, [start_array,{string,<<65533/utf8,$b,$l,$a,$h>>},end_array,end_json]}.
 {json, "unpaired_surrogate_replaced.json"}.
 {jsx_flags, [loose_unicode]}.
diff --git a/test/cases/zero.test b/test/cases/zero.test
index cd072a1..9515a85 100644
--- a/test/cases/zero.test
+++ b/test/cases/zero.test
@@ -4,9 +4,9 @@
  end_array,
  {integer,0},
  start_object,
- {key,"key"},
+ {key,<<"key">>},
  {integer,0},
- {key,"another key"},
+ {key,<<"another key">>},
  {integer,0},
  end_object,
  {integer,0},