diff --git a/jupyter_core/tests/test_command.py b/jupyter_core/tests/test_command.py
index 4c8c7d0f..f7e4b7d7 100644
--- a/jupyter_core/tests/test_command.py
+++ b/jupyter_core/tests/test_command.py
@@ -17,6 +17,15 @@
 )
 
 
+resetenv = patch.dict(os.environ)
+
+def setup_module():
+    resetenv.start()
+    os.environ.pop('JUPYTER_PREFER_ENV_PATH')
+
+def teardown_module():
+    resetenv.stop()
+
 def get_jupyter_output(cmd):
     """Get output of a jupyter command"""
     if not isinstance(cmd, list):
diff --git a/jupyter_core/tests/test_paths.py b/jupyter_core/tests/test_paths.py
index e59f46c4..6c5a49d3 100644
--- a/jupyter_core/tests/test_paths.py
+++ b/jupyter_core/tests/test_paths.py
@@ -48,6 +48,17 @@
 
 jupyter_config_env = '/jupyter-cfg'
 config_env = patch.dict('os.environ', {'JUPYTER_CONFIG_DIR': jupyter_config_env})
+prefer_env = patch.dict('os.environ', {'JUPYTER_PREFER_ENV_PATH': 'True'})
+
+resetenv = patch.dict(os.environ)
+
+def setup_module():
+    resetenv.start()
+    os.environ.pop('JUPYTER_PREFER_ENV_PATH')
+
+def teardown_module():
+    resetenv.stop()
+
 
 
 def realpath(path):
@@ -55,7 +66,6 @@ def realpath(path):
 
 home_jupyter = realpath('~/.jupyter')
 
-
 def test_envset():
     true_values = ['', 'True', 'on', 'yes', 'Y', '1', 'anything']
     false_values = ['n', 'No', 'N', 'fAlSE', '0', '0.0', 'Off']
@@ -199,7 +209,7 @@ def test_jupyter_path_no_user_site():
     assert path[1] == paths.ENV_JUPYTER_PATH[0]
 
 def test_jupyter_path_prefer_env():
-    with patch.dict('os.environ', {'JUPYTER_PREFER_ENV_PATH': 'true'}):
+    with prefer_env:
         path = jupyter_path()
     assert path[0] == paths.ENV_JUPYTER_PATH[0]
     assert path[1] == jupyter_data_dir()
@@ -241,7 +251,7 @@ def test_jupyter_config_path_no_user_site():
 
 
 def test_jupyter_config_path_prefer_env():
-    with patch.dict('os.environ', {'JUPYTER_PREFER_ENV_PATH': 'true'}):
+    with prefer_env:
         path = jupyter_config_path()
     assert path[0] == paths.ENV_CONFIG_PATH[0]
     assert path[1] == jupyter_config_dir()