diff --git a/datasette/app.py b/datasette/app.py
index 04e26a46..da9227d1 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -281,7 +281,7 @@ class Datasette:
                 raise
         self.crossdb = crossdb
         self.nolock = nolock
-        if memory or crossdb or (not self.files and memory is not False):
+        if memory or crossdb or not self.files:
             self.add_database(
                 Database(self, is_mutable=False, is_memory=True), name="_memory"
             )
diff --git a/tests/conftest.py b/tests/conftest.py
index 1306c407..e122d0d9 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -25,18 +25,12 @@ UNDOCUMENTED_PERMISSIONS = {
 }
 
 
-@pytest.fixture(scope="session")
-def event_loop():
-    return asyncio.get_event_loop()
-
-
-@pytest_asyncio.fixture(scope="session")
+@pytest_asyncio.fixture
 async def ds_client():
     from datasette.app import Datasette
     from .fixtures import METADATA, PLUGINS_DIR
 
     ds = Datasette(
-        memory=False,
         metadata=METADATA,
         plugins_dir=PLUGINS_DIR,
         settings={
@@ -51,12 +45,14 @@ async def ds_client():
     from .fixtures import TABLES, TABLE_PARAMETERIZED_SQL
 
     db = ds.add_memory_database("fixtures")
+    ds.remove_database("_memory")
 
     def prepare(conn):
-        conn.executescript(TABLES)
-        for sql, params in TABLE_PARAMETERIZED_SQL:
-            with conn:
-                conn.execute(sql, params)
+        if not conn.execute("select count(*) from sqlite_master").fetchone()[0]:
+            conn.executescript(TABLES)
+            for sql, params in TABLE_PARAMETERIZED_SQL:
+                with conn:
+                    conn.execute(sql, params)
 
     await db.execute_write_fn(prepare)
     return ds.client
diff --git a/tests/plugins/my_plugin_2.py b/tests/plugins/my_plugin_2.py
index 4f7bf08c..d588342c 100644
--- a/tests/plugins/my_plugin_2.py
+++ b/tests/plugins/my_plugin_2.py
@@ -117,7 +117,12 @@ def actor_from_request(datasette, request):
 def permission_allowed(datasette, actor, action):
     # Testing asyncio version of permission_allowed
     async def inner():
-        assert 2 == (await datasette.get_database().execute("select 1 + 1")).first()[0]
+        assert (
+            2
+            == (
+                await datasette.get_database("_internal").execute("select 1 + 1")
+            ).first()[0]
+        )
         if action == "this_is_allowed_async":
             return True
         elif action == "this_is_denied_async":