diff --git a/.travis.yml b/.travis.yml
index adca6b6c..3df2a610 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,8 @@ language: erlang
 sudo: false
 install: "true" # don't let travis run get-deps
 otp_release:
+  - 21.0
+  - 20.0
   - 19.1
   - 18.3
   - 17.5
diff --git a/include/wm_compat.hrl b/include/wm_compat.hrl
new file mode 100644
index 00000000..672f2619
--- /dev/null
+++ b/include/wm_compat.hrl
@@ -0,0 +1,7 @@
+-ifndef(deprecate_stacktrace).
+-define(STPATTERN(Pattern), Pattern).
+-define(STACKTRACE, erlang:get_stacktrace()).
+-else.
+-define(STPATTERN(Pattern), Pattern:__STACKTRACE).
+-define(STACKTRACE, __STACKTRACE).
+-endif.
diff --git a/include/wm_resource.hrl b/include/wm_resource.hrl
index 588405df..3381669c 100644
--- a/include/wm_resource.hrl
+++ b/include/wm_resource.hrl
@@ -1 +1 @@
--record(wm_resource, {module, modstate, modexports, trace}).
+-record(wm_resource, {module, modstate, trace}).
diff --git a/rebar.config b/rebar.config
index ea770995..9b04df9e 100644
--- a/rebar.config
+++ b/rebar.config
@@ -5,7 +5,7 @@
 
 {xref_checks, [undefined_function_calls]}.
 
-{deps, [{mochiweb, "2.12.2"}]}.
+{deps, [{mochiweb, "2.18.0"}]}.
 
 {eunit_opts, [
               no_tty,
@@ -15,8 +15,7 @@
 {profiles,
  [{test,
    [{deps, [meck,
-            {ibrowse, {git, "git://github.com/cmullaparthi/ibrowse.git", {tag, "v4.0.2"}}},
-            {eunit_formatters, {git, "git://github.com/seancribbs/eunit_formatters", {branch, "master"}}}
+            {ibrowse, "4.4.0"}
            ]},
     {erl_opts, [debug_info]}
    ]}
diff --git a/rebar.config.script b/rebar.config.script
index 2dba9a9f..9679562d 100644
--- a/rebar.config.script
+++ b/rebar.config.script
@@ -11,4 +11,15 @@ Config1 = case hd(OtpVersion) =:= $R andalso OtpVersion < "R15B02" of
                           CONFIG ++ [{erl_opts, HashDefine}]
                   end;
               false -> CONFIG
-          end.
+          end,
+if
+    OtpVersion >= "21" ->
+        case lists:keysearch(erl_opts, 1, Config1) of
+            {value, {erl_opts, Opts2}} ->
+                lists:keyreplace(erl_opts, 1, Config1, {erl_opts, [{d, deprecate_stacktrace}|Opts2]});
+            false ->
+                [{erl_opts, [{d, deprecate_stacktrace}]}|Config1]
+        end;
+    true ->
+        Config1
+end.
diff --git a/rebar.lock b/rebar.lock
index 57d5070b..4bc80524 100644
--- a/rebar.lock
+++ b/rebar.lock
@@ -1,6 +1,6 @@
 {"1.1.0",
-[{<<"mochiweb">>,{pkg,<<"mochiweb">>,<<"2.12.2">>},0}]}.
+[{<<"mochiweb">>,{pkg,<<"mochiweb">>,<<"2.18.0">>},0}]}.
 [
 {pkg_hash,[
- {<<"mochiweb">>, <<"80804AD342AFA3D7F3524040D4EED66CE74B17A555DE454AC85B07C479928E46">>}]}
+ {<<"mochiweb">>, <<"EB55F1DB3E6E960FAC4E6DB4E2DB9EC3602CC9F30B86CD1481D56545C3145D2E">>}]}
 ].
diff --git a/src/webmachine.app.src b/src/webmachine.app.src
index ad14f7b1..363e92d0 100644
--- a/src/webmachine.app.src
+++ b/src/webmachine.app.src
@@ -23,7 +23,7 @@
     %% string() for the "Server" response header
    ]},
 
-  {contributors,["Sean Cribbs", "Joe DeVivo" "Bryan Fink",
+  {maintainers,["Sean Cribbs", "Joe DeVivo", "Bryan Fink",
                  "Kelly McLaughlin", "Jared Morrow", "Andy Gross",
                  "Steve Vinoski"]},
   {licenses,["Apache"]},
diff --git a/src/webmachine_app.erl b/src/webmachine_app.erl
index 35fa74a3..0c15a08c 100644
--- a/src/webmachine_app.erl
+++ b/src/webmachine_app.erl
@@ -27,7 +27,7 @@
 
 -include("webmachine_logger.hrl").
 
--define(QUIP, "cafe not found").
+-define(QUIP, "greased slide to failure").
 
 %% @spec start(_Type, _StartArgs) -> ServerRet
 %% @doc application start callback for webmachine.
diff --git a/src/webmachine_decision_core.erl b/src/webmachine_decision_core.erl
index 4a50d09a..34263895 100644
--- a/src/webmachine_decision_core.erl
+++ b/src/webmachine_decision_core.erl
@@ -23,6 +23,13 @@
 -author('Bryan Fink <bryan@basho.com>').
 -export([handle_request/2]).
 -include("webmachine_logger.hrl").
+-include("wm_compat.hrl").
+
+%% Suppress Erlang/OTP 21 warnings about the new method to retrieve
+%% stacktraces.
+-ifdef(OTP_RELEASE).
+-compile({nowarn_deprecated_function, [{erlang, get_stacktrace, 0}]}).
+-endif.
 
 handle_request(Resource, ReqState) ->
     _ = [erase(X) || X <- [decision, code, req_body, bytes_written, tmp_reqstate]],
@@ -31,8 +38,8 @@ handle_request(Resource, ReqState) ->
     try
         d(v3b13)
     catch
-        error:_ ->
-            error_response(erlang:get_stacktrace())
+        ?STPATTERN(error:_Reason) ->
+            error_response(?STACKTRACE)
     end.
 
 wrcall(X) ->
diff --git a/src/webmachine_dispatcher.erl b/src/webmachine_dispatcher.erl
index dffa9aa7..280fdbab 100644
--- a/src/webmachine_dispatcher.erl
+++ b/src/webmachine_dispatcher.erl
@@ -628,7 +628,7 @@ make_reqdata(Path) ->
     MochiReq = mochiweb_request:new(testing, 'GET', Path, {1, 1},
                                     mochiweb_headers:make([])),
     Req = webmachine:new_request(mochiweb, MochiReq),
-    {RD, _} = Req:get_reqdata(),
+    {RD, _} = webmachine_request:get_reqdata(Req),
     RD.
 
 -endif.
diff --git a/src/webmachine_mochiweb.erl b/src/webmachine_mochiweb.erl
index 6b59daee..32d3b1d5 100644
--- a/src/webmachine_mochiweb.erl
+++ b/src/webmachine_mochiweb.erl
@@ -63,7 +63,7 @@ start(Options) ->
     webmachine_router:init_routes(DGroup, DispatchList),
     _ = [application_set_unless_env_or_undef(K, V) || {K, V} <- WMOptions],
     MochiName = list_to_atom(to_list(PName) ++ "_mochiweb"),
-    LoopFun = fun(X) -> loop(DGroup, X) end,
+    LoopFun = fun(X) -> ?MODULE:loop(DGroup, X) end,
     mochiweb_http:start([{name, MochiName}, {loop, LoopFun} | OtherOptions]).
 
 stop() ->
diff --git a/src/webmachine_resource.erl b/src/webmachine_resource.erl
index ada1ac1c..e9a072cb 100644
--- a/src/webmachine_resource.erl
+++ b/src/webmachine_resource.erl
@@ -17,9 +17,10 @@
 -module(webmachine_resource).
 -author('Justin Sheehy <justin@basho.com>').
 -author('Andy Gross <andy@basho.com>').
--export([new/4, wrap/2]).
+-export([new/3, wrap/2]).
 -export([do/3,log_d/2,stop/1]).
 
+-include("wm_compat.hrl").
 -include("wm_resource.hrl").
 -include("wm_reqdata.hrl").
 -include("wm_reqstate.hrl").
@@ -27,11 +28,22 @@
 -type t() :: #wm_resource{}.
 -export_type([t/0]).
 
-new(R_Mod, R_ModState, R_ModExports, R_Trace) ->
+-define(CALLBACK_ARITY, 2).
+
+%% Suppress Erlang/OTP 21 warnings about the new method to retrieve
+%% stacktraces.
+-ifdef(OTP_RELEASE).
+-compile({nowarn_deprecated_function, [{erlang, get_stacktrace, 0}]}).
+-endif.
+
+new(R_Mod, R_ModState, R_Trace) ->
+    case erlang:module_loaded(R_Mod) of
+        false -> code:ensure_loaded(R_Mod);
+        true -> ok
+    end,
     #wm_resource{
        module = R_Mod,
        modstate = R_ModState,
-       modexports = R_ModExports,
        trace = R_Trace
       }.
 
@@ -118,15 +130,13 @@ default(_) ->
 wrap(Mod, Args) ->
     case Mod:init(Args) of
         {ok, ModState} ->
-            {ok, webmachine_resource:new(Mod, ModState,
-                           orddict:from_list(Mod:module_info(exports)), false)};
+            {ok, webmachine_resource:new(Mod, ModState, false)};
         {{trace, Dir}, ModState} ->
             {ok, File} = open_log_file(Dir, Mod),
             log_decision(File, v3b14),
             log_call(File, attempt, Mod, init, Args),
             log_call(File, result, Mod, init, {{trace, Dir}, ModState}),
-            {ok, webmachine_resource:new(Mod, ModState,
-                orddict:from_list(Mod:module_info(exports)), File)};
+            {ok, webmachine_resource:new(Mod, ModState, File)};
         _ ->
             {stop, bad_init_arg}
     end.
@@ -136,7 +146,6 @@ do(#wm_resource{}=Res, Fun, ReqProps) ->
 do(Fun, ReqProps,
    #wm_resource{
       module=R_Mod,
-      modexports=R_ModExports,
       trace=R_Trace
      }=Req)
   when is_atom(Fun) andalso is_list(ReqProps) ->
@@ -155,21 +164,20 @@ do(Fun, ReqProps,
     %% Do not need the embedded state anymore
     TrimData = ReqData#wm_reqdata{wm_state=undefined},
     {Reply,
-     webmachine_resource:new(R_Mod, NewModState, R_ModExports, R_Trace),
+     webmachine_resource:new(R_Mod, NewModState, R_Trace),
      ReqState#wm_reqstate{reqdata=TrimData}}.
 
 handle_wm_call(Fun, ReqData,
                #wm_resource{
                   module=R_Mod,
                   modstate=R_ModState,
-                  modexports=R_ModExports,
                   trace=R_Trace
                  }=Req) ->
     case default(Fun) of
         no_default ->
             resource_call(Fun, ReqData, Req);
         Default ->
-            case orddict:is_key(Fun, R_ModExports) of
+            case erlang:function_exported(R_Mod, Fun, ?CALLBACK_ARITY) of
                 true ->
                     resource_call(Fun, ReqData, Req);
                 false ->
@@ -200,12 +208,13 @@ resource_call(F, ReqData,
         _ -> log_call(R_Trace, attempt, R_Mod, F, [ReqData, R_ModState])
     end,
     Result = try
+        %% Note: the argument list must match the definition of CALLBACK_ARITY
         apply(R_Mod, F, [ReqData, R_ModState])
-    catch C:R ->
-            Reason = {C, R, trim_trace(erlang:get_stacktrace())},
+    catch ?STPATTERN(C:R) ->
+            Reason = {C, R, trim_trace(?STACKTRACE)},
             {{error, Reason}, ReqData, R_ModState}
     end,
-        case R_Trace of
+    case R_Trace of
         false -> nop;
         _ -> log_call(R_Trace, result, R_Mod, F, Result)
     end,
diff --git a/test/decision_core_test.erl b/test/decision_core_test.erl
index 5b3f8eca..39a2b9ae 100644
--- a/test/decision_core_test.erl
+++ b/test/decision_core_test.erl
@@ -17,10 +17,20 @@
 
 -ifdef(TEST).
 
+-include("wm_compat.hrl").
 -include("wm_reqdata.hrl").
 -include_lib("eunit/include/eunit.hrl").
 
--compile(export_all).
+-export([size_stream_raises_error/2, process_post_for_created_p11/3, get_streamed_body/2, send_streamed_body/2,
+         accept_text/2, writer_response/2, known_length_body/2, range_response/2, stream_content_md5/0,
+         validate_checksum_for_md5stream/3, process_post_for_md5_stream/3, init/1, service_available/2,
+         validate_content_checksum/2, is_authorized/2, allowed_methods/2, known_methods/2, uri_too_long/2,
+         known_content_type/2, valid_entity_length/2, malformed_request/2, forbidden/2, valid_content_headers/2,
+         content_types_provided/2, content_types_accepted/2, language_available/2, charsets_provided/2,
+         encodings_provided/2, resource_exists/2, generate_etag/2, last_modified/2, moved_permanently/2,
+         moved_temporarily/2, previously_existed/2, allow_missing_post/2, post_is_create/2, process_post/2,
+         create_path/2, is_conflict/2, multiple_choices/2, base_uri/2, base_uri_add_slash/1, expires/2,
+         delete_resource/2, delete_completed/2, to_html/2]).
 
 -define(RESOURCE, atom_to_list(?MODULE)).
 -define(RESOURCE_PATH, "/" ++ ?RESOURCE).
@@ -35,6 +45,12 @@ md5(Bin) ->
     crypto:md5(Bin).
 -endif.
 
+%% Suppress Erlang/OTP 21 warnings about the new method to retrieve
+%% stacktraces.
+-ifdef(OTP_RELEASE).
+-compile({nowarn_deprecated_function, [{erlang, get_stacktrace, 0}]}).
+-endif.
+
 -define(HTTP_1_0_METHODS, ['GET', 'POST', 'HEAD']).
 -define(HTTP_1_1_METHODS, ['GET', 'HEAD', 'POST', 'PUT', 'DELETE', 'TRACE',
                            'CONNECT', 'OPTIONS']).
@@ -320,8 +336,8 @@ setup() ->
         meck:new(webmachine_resource, MeckOpts),
         Ctx
     catch
-        T:E ->
-            io:format(user, "~n~p : ~p : ~p", [T, E, erlang:get_stacktrace()]),
+        ?STPATTERN(T:E) ->
+            io:format(user, "~n~p : ~p : ~p", [T, E, ?STACKTRACE]),
             error(setup_failed)
     end.
 
diff --git a/test/wm_integration_test.erl b/test/wm_integration_test.erl
index 9aac6413..63b83521 100644
--- a/test/wm_integration_test.erl
+++ b/test/wm_integration_test.erl
@@ -17,8 +17,6 @@
 -include_lib("eunit/include/eunit.hrl").
 -include("webmachine.hrl").
 
--compile([export_all]).
-
 integration_test_() ->
     {foreach,
      %% Setup