diff --git a/tests/conftest.py b/tests/conftest.py
index 5cc3042..86debe7 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -8,12 +8,19 @@
 from .utils import check_for_iface, check_backend_support, modify_backend_list
 
 
+# copy all backends so we can mutate it.This variable is used in generate
+# tests to allow us to target a single backend without changing _ALL_BACKENDS
+
+_UPDATED_BACKENDS = list(_ALL_BACKENDS)
+
+
 def pytest_generate_tests(metafunc):
+    global _UPDATED_BACKENDS
     name = metafunc.config.getoption("--backend")
-    modify_backend_list(name, _ALL_BACKENDS)
+    modify_backend_list(name, _UPDATED_BACKENDS)
 
 
-@pytest.fixture(params=_ALL_BACKENDS)
+@pytest.fixture(params=_UPDATED_BACKENDS)
 def backend(request):
     return request.param