diff --git a/.gitignore b/.gitignore
index e3e5e72..c6154b9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,10 +1,15 @@
 .eunit
+.rebar
 .jiffy.dev
 *.app
 *.beam
+*.d
 *.o
 *.so
+_build
+compile_commands.json
 deps
 erln8.config
 hexer.config
+rebar.lock
 TEST-*.xml
diff --git a/.travis.yml b/.travis.yml
index fa26d15..4762c65 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,17 +3,15 @@ notifications:
   email: paul.joseph.davis@gmail.com
 script: make check
 otp_release:
+   - 19.1
+   - 19.0
+   - 18.3
+   - 18.2
    - 17.5
    - 17.4
-   - 17.3
-   - 17.1
-   - 17.0
    - R16B03-1
    - R16B02
-   - R16B01
    - R15B03
    - R15B02
-   - R15B01
    - R14B04
    - R14B03
-   - R14B02
diff --git a/Makefile b/Makefile
index 025486e..f781311 100644
--- a/Makefile
+++ b/Makefile
@@ -15,17 +15,7 @@ distclean: clean
 	git clean -fxd
 
 
-devmarker:
-	@touch .jiffy.dev
-
-
-depends: devmarker
-	@if test ! -d ./deps/proper; then \
-		$(REBAR) get-deps; \
-	fi
-
-
-build: depends
+build:
 	$(REBAR) compile
 
 
diff --git a/enc b/enc
new file mode 100755
index 0000000..239a351
Binary files /dev/null and b/enc differ
diff --git a/rebar.config b/rebar.config
index 9d26448..33b8186 100644
--- a/rebar.config
+++ b/rebar.config
@@ -33,13 +33,8 @@
 ]}.
 
 {eunit_opts, [
-    verbose,
-    {report, {
-        eunit_surefire, [{dir,"."}]
-    }}
-]}.
-
-{plugins, [
-    rebar_gdb_plugin
+    verbose
 ]}.
 
+{pre_hooks, [{"", compile, "./enc compile"}]}.
+{post_hooks, [{"", clean, "./enc clean"}]}.
diff --git a/rebar.config.script b/rebar.config.script
index 8a0049d..42bc6ef 100644
--- a/rebar.config.script
+++ b/rebar.config.script
@@ -1,37 +1,18 @@
 % This file is part of Jiffy released under the MIT license.
 % See the LICENSE file for more information.
-
-% Only include PropEr as a dependency when the JIFFY_DEV
-% environment variable is defined. This allows downstream
-% applications to avoid requiring PropEr.
 %
-% This script is based on the example provided with Rebar.
-
-ErlOpts = [{d, 'JIFFY_DEV'}],
+% Only run the EQC checks when EQC is present.
 
-Proper = [
-    {proper, ".*", {git, "git://github.com/manopapad/proper.git", "master"}}
-],
+HaveEQC = code:which(eqc) =/= non_existing,
 
-ConfigPath = filename:dirname(SCRIPT),
-DevMarker = filename:join([ConfigPath, ".jiffy.dev"]),
+ErlOpts = if not HaveEQC -> []; true ->
+    [{d, 'HAVE_EQC'}]
+end,
 
-case filelib:is_file(DevMarker) of
-    true ->
-        % Don't override existing dependencies
-        Config0 = case lists:keyfind(deps, 1, CONFIG) of
-            false ->
-                CONFIG ++ [{deps, Proper}];
-            {deps, DepsList} ->
-                lists:keyreplace(deps, 1, CONFIG, {deps, DepsList ++ Proper})
-        end,
-        Config1 = case lists:keyfind(erl_opts, 1, Config0) of
-            false ->
-                Config0 ++ [{erl_opts, ErlOpts}];
-            {erl_opts, Opts} ->
-                NewOpts = {erl_opts, Opts ++ ErlOpts},
-                lists:keyreplace(erl_opts, 1, Config0, NewOpts)
-        end;
+case lists:keyfind(erl_opts, 1, CONFIG) of
+    {erl_opts, Opts} ->
+        NewOpts = {erl_opts, Opts ++ ErlOpts},
+        lists:keyreplace(erl_opts, 1, CONFIG, NewOpts);
     false ->
-        CONFIG
+        CONFIG ++ [{erl_opts, ErlOpts}]
 end.
diff --git a/test/jiffy_01_yajl_tests.erl b/test/jiffy_01_yajl_tests.erl
index aedaf71..689c880 100644
--- a/test/jiffy_01_yajl_tests.erl
+++ b/test/jiffy_01_yajl_tests.erl
@@ -5,6 +5,7 @@
 
 
 -include_lib("eunit/include/eunit.hrl").
+-include("jiffy_util.hrl").
 
 
 yajl_test_() ->
@@ -19,7 +20,7 @@ gen({Name, Json, Erl}) ->
 
 
 read_cases() ->
-    CasesPath = filename:join(["..", "test", "cases", "*.json"]),
+    CasesPath = cases_path("*.json"),
     FileNames = lists:sort(filelib:wildcard(CasesPath)),
     lists:map(fun(F) -> make_pair(F) end, FileNames).
 
diff --git a/test/jiffy_10_short_double_tests.erl b/test/jiffy_10_short_double_tests.erl
index d66e1ea..0b099c1 100644
--- a/test/jiffy_10_short_double_tests.erl
+++ b/test/jiffy_10_short_double_tests.erl
@@ -8,7 +8,8 @@
 -include("jiffy_util.hrl").
 
 
-filename() -> "../test/cases/short-doubles.txt".
+filename() ->
+    cases_path("short-doubles.txt").
 
 
 short_double_test_() ->
diff --git a/test/jiffy_11_proper_tests.erl b/test/jiffy_11_proper_tests.erl
deleted file mode 100644
index 23aa38d..0000000
--- a/test/jiffy_11_proper_tests.erl
+++ /dev/null
@@ -1,185 +0,0 @@
-% This file is part of Jiffy released under the MIT license.
-% See the LICENSE file for more information.
-
--module(jiffy_11_proper_tests).
-
--ifdef(JIFFY_DEV).
-
--include_lib("proper/include/proper.hrl").
--include_lib("eunit/include/eunit.hrl").
--include("jiffy_util.hrl").
-
-opts() ->
-    [
-        {max_size, 15},
-        {numtests, 1000}
-    ].
-
-run(Name) ->
-    {msg("~s", [Name]), [
-        {timeout, 300, ?_assert(proper:quickcheck(?MODULE:Name(), opts()))}
-    ]}.
-
-proper_encode_decode_test_() ->
-    [
-        run(prop_enc_dec),
-        run(prop_enc_dec_pretty),
-        run(prop_dec_trailer),
-        run(prop_enc_no_crash),
-        run(prop_dec_no_crash_bin),
-        run(prop_dec_no_crash_any)
-    ].
-
-prop_enc_dec() ->
-    ?FORALL(Data, json(),
-        begin
-            %io:format(standard_error, "Data: ~p~n", [Data]),
-            Data == jiffy:decode(jiffy:encode(Data))
-        end
-    ).
-
-prop_dec_trailer() ->
-    ?FORALL({T1, T2}, {json(), json()},
-        begin
-            B1 = jiffy:encode(T1),
-            B2 = jiffy:encode(T2),
-            Combiners = [
-                <<" ">>,
-                <<"\r\t">>,
-                <<"\n   \t">>,
-                <<"                     ">>
-            ],
-            lists:foreach(fun(Comb) ->
-                Bin = <<B1/binary, Comb/binary, B2/binary>>,
-                {has_trailer, T1, Rest} = jiffy:decode(Bin, [return_trailer]),
-                T2 = jiffy:decode(Rest)
-            end, Combiners),
-            true
-        end
-    ).
-
--ifndef(JIFFY_NO_MAPS).
-to_map_ejson({Props}) ->
-    NewProps = [{K, to_map_ejson(V)} || {K, V} <- Props],
-    maps:from_list(NewProps);
-to_map_ejson(Vals) when is_list(Vals) ->
-    [to_map_ejson(V) || V <- Vals];
-to_map_ejson(Val) ->
-    Val.
-
-prop_map_enc_dec() ->
-    ?FORALL(Data, json(),
-        begin
-            MapData = to_map_ejson(Data),
-            MapData == jiffy:decode(jiffy:encode(MapData), [return_maps])
-        end
-    ).
--endif.
-
-prop_enc_dec_pretty() ->
-    ?FORALL(Data, json(),
-        begin
-            Data == jiffy:decode(jiffy:encode(Data, [pretty]))
-        end
-    ).
-
-prop_enc_no_crash() ->
-    ?FORALL(Data, any(), begin catch jiffy:encode(Data), true end).
-
-prop_dec_no_crash_bin() ->
-    ?FORALL(Data, binary(), begin catch jiffy:decode(Data), true end).
-
-prop_dec_no_crash_any() ->
-    ?FORALL(Data, any(), begin catch jiffy:decode(Data), true end).
-
-
-% JSON Generation
-
-
-json_null() ->
-    null.
-
-
-json_boolean() ->
-    oneof([true, false]).
-
-
-json_number() ->
-    oneof([integer(), float()]).
-
-
-json_string() ->
-    escaped_utf8_bin().
-
-
-json_list(S) when S =< 0 ->
-    [];
-json_list(S) ->
-    ?LETSHRINK(
-        [ListSize],
-        [integer(0, S)],
-        vector(ListSize, json_text(S - ListSize))
-    ).
-
-
-json_object(S) when S =< 0 ->
-    {[]};
-json_object(S) ->
-    ?LETSHRINK(
-        [ObjectSize],
-        [integer(0, S)],
-        {vector(ObjectSize, {json_string(), json_text(S - ObjectSize)})}
-    ).
-
-
-json_value() ->
-    oneof([
-        json_null(),
-        json_boolean(),
-        json_string(),
-        json_number()
-    ]).
-
-
-json_text(S) when S > 0 ->
-    ?LAZY(oneof([
-        json_list(S),
-        json_object(S)
-    ]));
-json_text(_) ->
-    json_value().
-
-
-json() ->
-    ?SIZED(S, json_text(S)).
-
-
-%% XXX: Add generators
-%
-% We should add generators that generate JSON binaries directly
-% so we can test things that aren't produced by the encoder.
-%
-% We should also have a version of the JSON generator that inserts
-% errors into the JSON that we can test for.
-
-
-escaped_utf8_bin() ->
-    ?SUCHTHAT(Bin,
-        ?LET(S, ?SUCHTHAT(L, list(escaped_char()), L /= []),
-        unicode:characters_to_binary(S, unicode, utf8)),
-        is_binary(Bin)
-    ).
-
-
-escaped_char() ->
-    ?LET(C, char(),
-        case C of
-            $" -> "\\\"";
-            C when C == 65534 -> 65533;
-            C when C == 65535 -> 65533;
-            C when C > 1114111 -> 1114111;
-            C -> C
-        end
-    ).
-
--endif.
diff --git a/test/jiffy_11_property_tests.erl b/test/jiffy_11_property_tests.erl
new file mode 100644
index 0000000..70d7333
--- /dev/null
+++ b/test/jiffy_11_property_tests.erl
@@ -0,0 +1,257 @@
+% This file is part of Jiffy released under the MIT license.
+% See the LICENSE file for more information.
+
+-module(jiffy_11_property_tests).
+
+-ifdef(HAVE_EQC).
+
+-include_lib("eqc/include/eqc.hrl").
+-include_lib("eunit/include/eunit.hrl").
+-include("jiffy_util.hrl").
+
+
+property_test_() ->
+    [
+        run(prop_enc_dec),
+        run(prop_enc_dec_pretty),
+        run(prop_dec_trailer),
+        run(prop_enc_no_crash),
+        run(prop_dec_no_crash_bin),
+        run(prop_dec_no_crash_any)
+    ] ++ map_props().
+
+
+-ifndef(JIFFY_NO_MAPS).
+map_props() ->
+    [
+        run(prop_map_enc_dec)
+    ].
+-else.
+map_props() ->
+    [].
+-endif.
+
+
+prop_enc_dec() ->
+    ?FORALL(Data, json(), begin
+        Data == jiffy:decode(jiffy:encode(Data))
+    end).
+
+
+prop_dec_trailer() ->
+    ?FORALL({T1, Comb, T2}, {json(), combiner(), json()},
+        begin
+            B1 = jiffy:encode(T1),
+            B2 = jiffy:encode(T2),
+            Bin = <<B1/binary, Comb/binary, B2/binary>>,
+            {has_trailer, T1, Rest} = jiffy:decode(Bin, [return_trailer]),
+            T2 = jiffy:decode(Rest),
+            true
+        end
+    ).
+
+
+prop_enc_dec_pretty() ->
+    ?FORALL(Data, json(),
+        begin
+            Data == jiffy:decode(jiffy:encode(Data, [pretty]))
+        end
+    ).
+
+
+-ifndef(JIFFY_NO_MAPS).
+prop_map_enc_dec() ->
+    ?FORALL(Data, json(),
+        begin
+            MapData = to_map_ejson(Data),
+            MapData == jiffy:decode(jiffy:encode(MapData), [return_maps])
+        end
+    ).
+-endif.
+
+
+prop_enc_no_crash() ->
+    ?FORALL(Data, any(), begin catch jiffy:encode(Data), true end).
+
+
+prop_dec_no_crash_any() ->
+    ?FORALL(Data, any(), begin catch jiffy:decode(Data), true end).
+
+
+prop_dec_no_crash_bin() ->
+    ?FORALL(Data, binary(), begin catch jiffy:decode(Data), true end).
+
+
+opts() ->
+    [
+        {numtests, [1000]}
+    ].
+
+
+apply_opts(Prop) ->
+    apply_opts(Prop, opts()).
+
+
+apply_opts(Prop, []) ->
+    Prop;
+
+apply_opts(Prop, [{Name, Args} | Rest]) ->
+    NewProp = erlang:apply(eqc, Name, Args ++ [Prop]),
+    apply_opts(NewProp, Rest).
+
+
+log(F, A) ->
+    io:format(standard_error, F, A).
+
+
+run(Name) ->
+    Prop = apply_opts(?MODULE:Name()),
+    {msg("~s", [Name]), [
+        {timeout, 300, ?_assert(eqc:quickcheck(Prop))}
+    ]}.
+
+
+-ifndef(JIFFY_NO_MAPS).
+to_map_ejson({Props}) ->
+    NewProps = [{K, to_map_ejson(V)} || {K, V} <- Props],
+    maps:from_list(NewProps);
+to_map_ejson(Vals) when is_list(Vals) ->
+    [to_map_ejson(V) || V <- Vals];
+to_map_ejson(Val) ->
+    Val.
+-endif.
+
+
+% Random any term generation
+
+any() ->
+    ?SIZED(Size, any(Size)).
+
+
+any(0) ->
+    any_value();
+
+any(S) ->
+    oneof(any_value_types() ++ [
+        ?LAZY(any_list(S)),
+        ?LAZY(any_tuple(S))
+    ]).
+
+
+any_value() ->
+    oneof(any_value_types()).
+
+
+any_value_types() ->
+    [
+        largeint(),
+        int(),
+        real(),
+        atom(),
+        binary()
+    ].
+
+
+any_list(0) ->
+    [];
+
+any_list(Size) ->
+    ListSize = Size div 5,
+    vector(ListSize, any(Size div 2)).
+
+
+any_tuple(0) ->
+    {};
+
+any_tuple(Size) ->
+    ?LET(L, any_list(Size), list_to_tuple(L)).
+
+
+% JSON Generation
+
+json() ->
+    ?SIZED(Size, json(Size)).
+
+
+json(0) ->
+    oneof([
+        json_null(),
+        json_true(),
+        json_false(),
+        json_number(),
+        json_string()
+    ]);
+
+json(Size) ->
+    frequency([
+        {1, json_null()},
+        {1, json_true()},
+        {1, json_false()},
+        {1, json_number()},
+        {1, json_string()},
+        {5, ?LAZY(json_array(Size))},
+        {5, ?LAZY(json_object(Size))}
+    ]).
+
+
+json_null() ->
+    null.
+
+
+json_true() ->
+    true.
+
+
+json_false() ->
+    false.
+
+
+json_number() ->
+    oneof([largeint(), int(), real()]).
+
+
+json_string() ->
+    utf8().
+
+
+json_array(0) ->
+    [];
+
+json_array(Size) ->
+    ArrSize = Size div 5,
+    vector(ArrSize, json(Size div 2)).
+
+
+json_object(0) ->
+    {[]};
+json_object(Size) ->
+    ObjSize = Size div 5,
+    {vector(ObjSize, {json_string(), json(Size div 2)})}.
+
+
+combiner() ->
+    ?SIZED(
+        Size,
+        ?LET(
+            L,
+            vector((Size div 4) + 1, oneof([$\r, $\n, $\t, $\s])),
+            list_to_binary(L)
+        )
+    ).
+
+
+atom() ->
+    ?LET(L, ?SIZED(Size, vector(Size rem 254, char())), list_to_atom(L)).
+
+
+
+%% XXX: Add generators
+%
+% We should add generators that generate JSON binaries directly
+% so we can test things that aren't produced by the encoder.
+%
+% We should also have a version of the JSON generator that inserts
+% errors into the JSON that we can test for.
+
+
+-endif.
diff --git a/test/jiffy_util.hrl b/test/jiffy_util.hrl
index 51bd86a..4b714d9 100644
--- a/test/jiffy_util.hrl
+++ b/test/jiffy_util.hrl
@@ -25,3 +25,16 @@ enc(V) ->
 
 enc(V, Opts) ->
     iolist_to_binary(jiffy:encode(V, Opts)).
+
+
+%% rebar runs eunit with PWD as .eunit/
+%% rebar3 runs eunit with PWD as ./
+%% this adapts to the differences
+cases_path(Suffix) ->
+    {ok, Cwd} = file:get_cwd(),
+    Prefix = case filename:basename(Cwd) of
+        ".eunit" -> "..";
+        _ -> "."
+    end,
+    Path = "test/cases",
+    filename:join([Prefix, Path, Suffix]).