diff --git a/datasette/app.py b/datasette/app.py
index 09f281e3..2e90571a 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -1,4 +1,5 @@
 import asyncio
+from pydoc import plain
 from typing import Sequence, Union, Tuple, Optional, Dict, Iterable
 import asgi_csrf
 import collections
@@ -415,12 +416,19 @@ class Datasette:
             # Compare schema versions to see if we should skip it
             if schema_version == current_schema_versions.get(database_name):
                 continue
+            placeholders = "(?, ?, ?, ?)"
+            values = [database_name, str(db.path), db.is_memory, schema_version]
+            if db.path is None:
+                placeholders = "(?, null, ?, ?)"
+                values = [database_name, db.is_memory, schema_version]
             await internal_db.execute_write(
                 """
                 INSERT OR REPLACE INTO databases (database_name, path, is_memory, schema_version)
-                VALUES (?, ?, ?, ?)
-            """,
-                [database_name, str(db.path), db.is_memory, schema_version],
+                VALUES {}
+            """.format(
+                    placeholders
+                ),
+                values,
             )
             await populate_schema_tables(internal_db, db)
 
diff --git a/tests/test_internal_db.py b/tests/test_internal_db.py
index 351105ef..a666dd72 100644
--- a/tests/test_internal_db.py
+++ b/tests/test_internal_db.py
@@ -19,8 +19,12 @@ async def test_internal_databases(ds_client):
         )
     ).json()
     assert len(databases) == 2
-    assert databases[0]["database_name"] == "_internal"
-    assert databases[1]["database_name"] == "fixtures"
+    internal, fixtures = databases
+    assert internal["database_name"] == "_internal"
+    assert internal["is_memory"] == 1
+    assert internal["path"] is None
+    assert isinstance(internal["schema_version"], int)
+    assert fixtures["database_name"] == "fixtures"
 
 
 @pytest.mark.asyncio