diff --git a/rebar.config b/rebar.config
index 757f86c..552a5aa 100644
--- a/rebar.config
+++ b/rebar.config
@@ -1,6 +1,6 @@
 {erl_opts, [debug_info]}. %, fail_on_warning]}.
 
-{require_otp_vsn, "R14"}.
+{require_otp_vsn, "R15"}.
 
 {deps_dir, ["deps"]}.
 
diff --git a/src/bigwig.erl b/src/bigwig.erl
index 7280c79..4428db9 100644
--- a/src/bigwig.erl
+++ b/src/bigwig.erl
@@ -1,19 +1,19 @@
 -module(bigwig).
 -export([start/0, stop/0]).
 
-ensure_started(App) ->
-    case application:start(App) of
-        ok ->
-            ok;
-        {error, {already_started, App}} ->
-            ok
-    end.
-
 start() ->
-    ensure_started(crypto),
-    ensure_started(sasl),
-    ensure_started(cowboy),
-    application:start(bigwig).
-
+    start(bigwig).
 stop() ->
     application:stop(bigwig).
+start(App) ->
+    start_ok(App, application:start(App, permanent)).
+
+start_ok(_App, ok) ->
+    ok;
+start_ok(_App, {error, {already_started, _App}}) ->
+    ok;
+start_ok(App, {error, {not_started, Dep}}) ->
+    ok = start(Dep),
+    start(App);
+start_ok(_App, {error, Reason}) ->
+    erlang:error({app_start_failed, Reason}).