diff --git a/datasette/database.py b/datasette/database.py
index 4a0babfb64..554f9fbf70 100644
--- a/datasette/database.py
+++ b/datasette/database.py
@@ -32,6 +32,7 @@
 class Database:
     # For table counts stop at this many rows:
     count_limit = 10000
+    _thread_local_id_counter = 1
 
     def __init__(
         self,
@@ -43,6 +44,8 @@ def __init__(
         mode=None,
     ):
         self.name = None
+        self._thread_local_id = f"x{self._thread_local_id_counter}"
+        Database._thread_local_id_counter += 1
         self.route = None
         self.ds = ds
         self.path = path
@@ -278,11 +281,11 @@ async def execute_fn(self, fn):
 
         # threaded mode
         def in_thread():
-            conn = getattr(connections, self.name, None)
+            conn = getattr(connections, self._thread_local_id, None)
             if not conn:
                 conn = self.connect()
                 self.ds._prepare_connection(conn, self.name)
-                setattr(connections, self.name, conn)
+                setattr(connections, self._thread_local_id, conn)
             return fn(conn)
 
         return await asyncio.get_event_loop().run_in_executor(
diff --git a/tests/test_internals_database.py b/tests/test_internals_database.py
index edfc6bc7d9..eeaf8e9ada 100644
--- a/tests/test_internals_database.py
+++ b/tests/test_internals_database.py
@@ -721,3 +721,34 @@ async def test_hidden_tables(app_client):
         "r_parent",
         "r_rowid",
     ]
+
+
+@pytest.mark.asyncio
+async def test_replace_database(tmpdir):
+    path1 = str(tmpdir / "data1.db")
+    (tmpdir / "two").mkdir()
+    path2 = str(tmpdir / "two" / "data1.db")
+    sqlite3.connect(path1).executescript(
+        """
+        create table t (id integer primary key);
+        insert into t (id) values (1);
+        insert into t (id) values (2);
+    """
+    )
+    sqlite3.connect(path2).executescript(
+        """
+        create table t (id integer primary key);
+        insert into t (id) values (1);
+    """
+    )
+    datasette = Datasette([path1])
+    db = datasette.get_database("data1")
+    count = (await db.execute("select count(*) from t")).first()[0]
+    assert count == 2
+    # Now replace that database
+    datasette.get_database("data1").close()
+    datasette.remove_database("data1")
+    datasette.add_database(Database(datasette, path2), "data1")
+    db2 = datasette.get_database("data1")
+    count = (await db2.execute("select count(*) from t")).first()[0]
+    assert count == 1