diff --git a/tests/dummy_audio.py b/tests/dummy_audio.py
index 144f1a4..8e85d0a 100644
--- a/tests/dummy_audio.py
+++ b/tests/dummy_audio.py
@@ -6,7 +6,6 @@ tests of the core and backends.
 
 
 import pykka
-
 from mopidy import audio
 
 
diff --git a/tests/dummy_backend.py b/tests/dummy_backend.py
index 0ee3d2d..f8e6908 100644
--- a/tests/dummy_backend.py
+++ b/tests/dummy_backend.py
@@ -6,7 +6,6 @@ used in tests of the frontends.
 
 
 import pykka
-
 from mopidy import backend
 from mopidy.models import Playlist, Ref, SearchResult
 
diff --git a/tests/dummy_mixer.py b/tests/dummy_mixer.py
index 7cdffcc..b80e681 100644
--- a/tests/dummy_mixer.py
+++ b/tests/dummy_mixer.py
@@ -1,5 +1,4 @@
 import pykka
-
 from mopidy import mixer
 
 
diff --git a/tests/test_frontend.py b/tests/test_frontend.py
index bd6c466..393c69e 100644
--- a/tests/test_frontend.py
+++ b/tests/test_frontend.py
@@ -1,15 +1,15 @@
 import sys
 from unittest import mock
 
+import pykka
+from mopidy import core
+
 import pytest
 from mopidy_raspberry_gpio import Extension
 from mopidy_raspberry_gpio import frontend as frontend_lib
 from mopidy_raspberry_gpio import pinconfig
 
-from mopidy import core
-from . import dummy_mixer
-from . import dummy_backend
-from . import dummy_audio
+from . import dummy_audio, dummy_backend, dummy_mixer
 
 deserialize = pinconfig.PinConfig().deserialize
 
@@ -23,6 +23,10 @@ dummy_config = {
 }
 
 
+def stop_mopidy_core():
+    pykka.ActorRegistry.stop_all()
+
+
 def dummy_mopidy_core():
     mixer = dummy_mixer.create_proxy()
     audio = dummy_audio.create_proxy()
@@ -43,6 +47,8 @@ def test_get_frontend_classes():
         "frontend", frontend_lib.RaspberryGPIOFrontend
     )
 
+    stop_mopidy_core()
+
 
 def test_frontend_handler_dispatch_play_pause():
     sys.modules["RPi"] = mock.Mock()
@@ -54,6 +60,8 @@ def test_frontend_handler_dispatch_play_pause():
 
     frontend.dispatch_input("play_pause")
 
+    stop_mopidy_core()
+
 
 def test_frontend_handler_dispatch_next():
     sys.modules["RPi"] = mock.Mock()
@@ -65,6 +73,8 @@ def test_frontend_handler_dispatch_next():
 
     frontend.dispatch_input("next")
 
+    stop_mopidy_core()
+
 
 def test_frontend_handler_dispatch_prev():
     sys.modules["RPi"] = mock.Mock()
@@ -76,6 +86,8 @@ def test_frontend_handler_dispatch_prev():
 
     frontend.dispatch_input("prev")
 
+    stop_mopidy_core()
+
 
 def test_frontend_handler_dispatch_volume_up():
     sys.modules["RPi"] = mock.Mock()
@@ -87,6 +99,8 @@ def test_frontend_handler_dispatch_volume_up():
 
     frontend.dispatch_input("volume_up")
 
+    stop_mopidy_core()
+
 
 def test_frontend_handler_dispatch_volume_down():
     sys.modules["RPi"] = mock.Mock()
@@ -98,6 +112,8 @@ def test_frontend_handler_dispatch_volume_down():
 
     frontend.dispatch_input("volume_down")
 
+    stop_mopidy_core()
+
 
 def test_frontend_handler_dispatch_invalid_event():
     sys.modules["RPi"] = mock.Mock()
@@ -110,6 +126,8 @@ def test_frontend_handler_dispatch_invalid_event():
     with pytest.raises(RuntimeError):
         frontend.dispatch_input("tomato")
 
+    stop_mopidy_core()
+
 
 def test_frontend_gpio_event():
     sys.modules["RPi"] = mock.Mock()
@@ -120,3 +138,5 @@ def test_frontend_gpio_event():
     )
 
     frontend.gpio_event(3)
+
+    stop_mopidy_core()