diff --git a/lib/mix/lib/mix/sync/lock.ex b/lib/mix/lib/mix/sync/lock.ex
index dc65e57713c..62369a6e0fe 100644
--- a/lib/mix/lib/mix/sync/lock.ex
+++ b/lib/mix/lib/mix/sync/lock.ex
@@ -97,7 +97,7 @@ defmodule Mix.Sync.Lock do
     opts = Keyword.validate!(opts, [:on_taken])
 
     hash = key |> :erlang.md5() |> Base.url_encode64(padding: false)
-    path = Path.join([System.tmp_dir!(), "mix_lock", hash])
+    path = Path.join(base_path(), hash)
 
     pdict_key = {__MODULE__, path}
     has_lock? = Process.get(pdict_key, false)
@@ -119,6 +119,13 @@ defmodule Mix.Sync.Lock do
     end
   end
 
+  defp base_path do
+    user = System.get_env("USER", "default")
+    path = Path.join([System.tmp_dir!(), "mix_lock_#{Base.url_encode64(user, padding: false)}"])
+    File.mkdir_p!(path)
+    path
+  end
+
   defp lock_disabled?(), do: System.get_env("MIX_OS_CONCURRENCY_LOCK") in ~w(0 false)
 
   defp lock(path, on_taken) do
diff --git a/lib/mix/lib/mix/sync/pubsub.ex b/lib/mix/lib/mix/sync/pubsub.ex
index 8c72406e944..b048f69f2a5 100644
--- a/lib/mix/lib/mix/sync/pubsub.ex
+++ b/lib/mix/lib/mix/sync/pubsub.ex
@@ -272,9 +272,16 @@ defmodule Mix.Sync.PubSub do
 
   defp hash(key), do: :erlang.md5(key)
 
+  defp base_path do
+    user = System.get_env("USER", "default")
+    path = Path.join([System.tmp_dir!(), "mix_pubsub_#{Base.url_encode64(user, padding: false)}"])
+    File.mkdir_p!(path)
+    path
+  end
+
   defp path(hash) do
     hash = Base.url_encode64(hash, padding: false)
-    Path.join([System.tmp_dir!(), "mix_pubsub", hash])
+    Path.join(base_path(), hash)
   end
 
   defp recv(socket, size, timeout \\ :infinity) do