diff --git a/src/apns.app.src b/src/apns.app.src
index 0c3efec..5050d37 100644
--- a/src/apns.app.src
+++ b/src/apns.app.src
@@ -13,6 +13,9 @@
   ]},
   {modules, []},
   {mod, {apns_app, []}},
+  {env, [
+      {openssl_command, "openssl"}
+  ]},
   {maintainers,["Inaka"]},
   {licenses,["Apache 2.0"]},
   {links,[{"Github","https://github.com/inaka/apns4erl"}]},
diff --git a/src/apns_utils.erl b/src/apns_utils.erl
index 4050cb9..65881d5 100644
--- a/src/apns_utils.erl
+++ b/src/apns_utils.erl
@@ -35,9 +35,10 @@
 -spec sign(binary()) -> binary().
 sign(Data) ->
   {ok, KeyPath} = application:get_env(apns, token_keyfile),
-  Command = "printf '" ++
-            binary_to_list(Data) ++
-            "' | openssl dgst -binary -sha256 -sign " ++ KeyPath ++ " | base64",
+  {ok, Openssl} = application:get_env(apns, openssl_command),
+  Command = "printf '" ++ binary_to_list(Data) ++
+            "' | " ++ Openssl ++ " dgst -binary -sha256 -sign " ++
+            KeyPath ++ " | base64",
   {0, Result} = apns_os:cmd(Command),
   strip_b64(list_to_binary(Result)).
 
@@ -67,3 +68,4 @@ seconds_to_timestamp(Secs) ->
 -spec strip_b64(binary()) -> binary().
 strip_b64(BS) ->
   binary:list_to_bin(binary:split(BS, [<<"\n">>, <<"=">>], [global])).
+