diff --git a/lib/spack/spack/test/conftest.py b/lib/spack/spack/test/conftest.py
index 53493eda910..5c5b3f84df7 100644
--- a/lib/spack/spack/test/conftest.py
+++ b/lib/spack/spack/test/conftest.py
@@ -38,6 +38,7 @@
 from spack.fetch_strategy import FetchError
 from spack.spec import Spec
 from spack.version import Version
+from spack.main import SpackCommand
 
 
 #
@@ -61,6 +62,16 @@ def clean_user_environment():
         ev.activate(active)
 
 
+#
+# Turn off Spack's shared mode if need be
+#
+@pytest.fixture(scope='session', autouse=True)
+def disable_shared():
+    if spack.config.get('config:shared'):
+        share = SpackCommand('share')
+        share('deactivate')
+
+
 # Hooks to add command line options or set other custom behaviors.
 # They must be placed here to be found by pytest. See:
 #