diff --git a/src/emqx_sys.erl b/src/emqx_sys.erl
index 65b939836..c61272e64 100644
--- a/src/emqx_sys.erl
+++ b/src/emqx_sys.erl
@@ -95,16 +95,14 @@ sysdescr() -> emqx_app:get_description().
 -spec(uptime() -> string()).
 uptime() ->
     {TotalWallClock, _} = erlang:statistics(wall_clock),
-    {D, {H, M, S}} = calendar:seconds_to_daystime(TotalWallClock div 1000),
-    List = [{D, " days"}, {H, " hours"}, {M, " minutes"}, {S, " seconds"}],
-    {_, Uptime} =
-        lists:foldl(fun({Time, Unit}, {NeedSkip, Acc}) ->
-            case Time =:= 0 andalso NeedSkip of
-                true -> {NeedSkip, Acc};
-                false -> {false, [[integer_to_list(Time), Unit] |Acc]}
-            end
-                    end, {true, []}, List),
-    lists:flatten(lists:join(", ", lists:reverse(Uptime))).
+    uptime(TotalWallClock div 1000).
+
+uptime(Seconds) ->
+    {D, {H, M, S}} = calendar:seconds_to_daystime(Seconds),
+    L0 = [{D, " days"}, {H, " hours"}, {M, " minutes"}, {S, " seconds"}],
+    L1 = lists:dropwhile(fun({K, _}) ->  K =:= 0 end, L0),
+    L2 = lists:map(fun({Time, Unit}) -> [integer_to_list(Time), Unit] end, L1),
+    lists:flatten(lists:join(", ", L2)).
 
 %% @doc Get sys datetime
 -spec(datetime() -> string()).
diff --git a/test/emqx_sys_SUITE.erl b/test/emqx_sys_SUITE.erl
index 29583524f..e7289cb38 100644
--- a/test/emqx_sys_SUITE.erl
+++ b/test/emqx_sys_SUITE.erl
@@ -34,7 +34,7 @@ end_per_suite(_Config) ->
     application:unload(emqx),
     ok = emqx_logger:set_log_level(error),
     ok.
-    
+
 % t_version(_) ->
 %     error('TODO').
 
@@ -42,10 +42,23 @@ end_per_suite(_Config) ->
 %     error('TODO').
 
 t_uptime(_) ->
-    ?assertEqual(<<"1 seconds">>, iolist_to_binary(emqx_sys:uptime(seconds, 1))),
-    ?assertEqual(<<"1 minutes, 0 seconds">>, iolist_to_binary(emqx_sys:uptime(seconds, 60))),
-    ?assertEqual(<<"1 hours, 0 minutes, 0 seconds">>, iolist_to_binary(emqx_sys:uptime(seconds, 3600))),
-    ?assertEqual(<<"1 days, 0 hours, 0 minutes, 0 seconds">>, iolist_to_binary(emqx_sys:uptime(seconds, 86400))).
+    ?assert(is_list(emqx_sys:uptime())),
+    ?assertEqual(<<"1 seconds">>, iolist_to_binary(emqx_sys:uptime(1))),
+    ?assertEqual(<<"1 minutes, 0 seconds">>, iolist_to_binary(emqx_sys:uptime(60))),
+    ?assertEqual(<<"1 hours, 0 minutes, 0 seconds">>, iolist_to_binary(emqx_sys:uptime(3600))),
+    ?assertEqual(<<"1 hours, 1 minutes, 1 seconds">>, iolist_to_binary(emqx_sys:uptime(3661))),
+    ?assertEqual(<<"1 days, 0 hours, 0 minutes, 0 seconds">>, iolist_to_binary(emqx_sys:uptime(86400))),
+    lists:map(fun({D, H, M, S}) ->
+        Expect = <<
+            (integer_to_binary(D))/binary, " days, ",
+            (integer_to_binary(H))/binary, " hours, ",
+            (integer_to_binary(M))/binary, " minutes, ",
+            (integer_to_binary(S))/binary, " seconds"
+        >>,
+        Actual = iolist_to_binary(emqx_sys:uptime(D * 86400 + H * 3600 + M * 60 + S)),
+        ?assertEqual(Expect, Actual)
+              end,
+        [{1, 2, 3, 4}, {10, 20, 30, 40}, {2222, 3, 56, 59}, {59, 23, 59, 59}]).
 
 % t_datetime(_) ->
 %     error('TODO').