diff --git a/lib/mix/lib/mix/tasks/cmd.ex b/lib/mix/lib/mix/tasks/cmd.ex
index cfe43466db2..1af11727c27 100644
--- a/lib/mix/lib/mix/tasks/cmd.ex
+++ b/lib/mix/lib/mix/tasks/cmd.ex
@@ -57,6 +57,10 @@ defmodule Mix.Tasks.Cmd do
   def run(args) do
     {opts, args} = OptionParser.parse_head!(args, strict: @switches)
 
+    if args == [] do
+      Mix.raise("Expected at least one argument in mix cmd")
+    end
+
     apps =
       opts
       |> Keyword.get_values(:app)
@@ -69,7 +73,7 @@ defmodule Mix.Tasks.Cmd do
     if apps == [] or Mix.Project.config()[:app] in apps do
       cmd_opts = Keyword.take(opts, [:cd])
 
-      case Mix.shell().cmd(Enum.join(args, " "), cmd_opts) do
+      case Mix.shell().cmd({hd(args), tl(args)}, cmd_opts) do
         0 -> :ok
         status -> exit(status)
       end
diff --git a/lib/mix/test/mix/tasks/cmd_test.exs b/lib/mix/test/mix/tasks/cmd_test.exs
index be437998539..6c738f2120a 100644
--- a/lib/mix/test/mix/tasks/cmd_test.exs
+++ b/lib/mix/test/mix/tasks/cmd_test.exs
@@ -4,22 +4,20 @@ defmodule Mix.Tasks.CmdTest do
   use MixTest.Case
 
   test "can be called multiple times" do
-    nl = os_newline()
     Mix.Task.run("cmd", ["echo", "hello"])
-    assert_received {:mix_shell, :run, ["hello" <> ^nl]}
-    Mix.Task.run("cmd", ["echo", "hello"])
-    assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+    assert_received {:mix_shell, :run, ["hello\n"]}
+    Mix.Task.run("cmd", ["echo", "hello world"])
+    assert_received {:mix_shell, :run, ["hello world\n"]}
   end
 
   test "runs the command for each app" do
     in_fixture("umbrella_dep/deps/umbrella", fn ->
       Mix.Project.in_project(:umbrella, ".", fn _ ->
         Mix.Task.run("cmd", ["echo", "hello"])
-        nl = os_newline()
         assert_received {:mix_shell, :info, ["==> bar"]}
-        assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+        assert_received {:mix_shell, :run, ["hello\n"]}
         assert_received {:mix_shell, :info, ["==> foo"]}
-        assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+        assert_received {:mix_shell, :run, ["hello\n"]}
       end)
     end)
   end
@@ -29,11 +27,10 @@ defmodule Mix.Tasks.CmdTest do
       in_fixture("umbrella_dep/deps/umbrella", fn ->
         Mix.Project.in_project(:umbrella, ".", fn _ ->
           Mix.Task.run("cmd", ["--app", "bar", "echo", "hello"])
-          nl = os_newline()
           assert_received {:mix_shell, :info, ["==> bar"]}
-          assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+          assert_received {:mix_shell, :run, ["hello\n"]}
           refute_received {:mix_shell, :info, ["==> foo"]}
-          refute_received {:mix_shell, :run, ["hello" <> ^nl]}
+          refute_received {:mix_shell, :run, ["hello\n"]}
         end)
       end)
     end)
@@ -44,11 +41,10 @@ defmodule Mix.Tasks.CmdTest do
       in_fixture("umbrella_dep/deps/umbrella", fn ->
         Mix.Project.in_project(:umbrella, ".", fn _ ->
           Mix.Task.run("cmd", ["--app", "bar", "--app", "foo", "echo", "hello"])
-          nl = os_newline()
           assert_received {:mix_shell, :info, ["==> bar"]}
-          assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+          assert_received {:mix_shell, :run, ["hello\n"]}
           assert_received {:mix_shell, :info, ["==> foo"]}
-          assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+          assert_received {:mix_shell, :run, ["hello\n"]}
         end)
       end)
     end)
diff --git a/lib/mix/test/mix/tasks/do_test.exs b/lib/mix/test/mix/tasks/do_test.exs
index 00b89af4e9d..8dd83f8205c 100644
--- a/lib/mix/test/mix/tasks/do_test.exs
+++ b/lib/mix/test/mix/tasks/do_test.exs
@@ -52,11 +52,10 @@ defmodule Mix.Tasks.DoTest do
       Mix.Project.in_project(:umbrella, ".", fn _ ->
         Mix.Tasks.Do.run(~w(--app bar compile --list + cmd echo hello))
 
-        nl = os_newline()
         assert_received {:mix_shell, :info, ["==> bar"]}
-        assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+        assert_received {:mix_shell, :run, ["hello\n"]}
         refute_received {:mix_shell, :info, ["==> foo"]}
-        refute_received {:mix_shell, :run, ["hello" <> ^nl]}
+        refute_received {:mix_shell, :run, ["hello\n"]}
       end)
     end)
   end
@@ -66,11 +65,10 @@ defmodule Mix.Tasks.DoTest do
       Mix.Project.in_project(:umbrella, ".", fn _ ->
         Mix.Tasks.Do.run(~w(--app bar --app foo compile --list + cmd echo hello))
 
-        nl = os_newline()
         assert_received {:mix_shell, :info, ["==> bar"]}
-        assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+        assert_received {:mix_shell, :run, ["hello\n"]}
         assert_received {:mix_shell, :info, ["==> foo"]}
-        assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+        assert_received {:mix_shell, :run, ["hello\n"]}
       end)
     end)
   end
@@ -105,13 +103,12 @@ defmodule Mix.Tasks.DoTest do
         Mix.Tasks.Do.run(["compile"])
         Mix.Tasks.Do.run(["--app", "bar", "--app", "foo", "e", "+", "p", "Foo"])
 
-        nl = os_newline()
         assert_received {:mix_shell, :info, ["==> bar"]}
-        assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+        assert_received {:mix_shell, :run, ["hello\n"]}
         assert_received {:mix_shell, :info, ["[\"Foo\"]"]}
 
         assert_received {:mix_shell, :info, ["==> foo"]}
-        assert_received {:mix_shell, :run, ["hello" <> ^nl]}
+        assert_received {:mix_shell, :run, ["hello\n"]}
         assert_received {:mix_shell, :info, ["[\"Foo\"]"]}
       end)
     end)