diff --git a/datasette/app.py b/datasette/app.py
index 03d1dacc..32a911c2 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -217,7 +217,10 @@ class Datasette:
         self._secret = secret or secrets.token_hex(32)
         self.files = tuple(files or []) + tuple(immutables or [])
         if config_dir:
-            self.files += tuple([str(p) for p in config_dir.glob("*.db")])
+            db_files = []
+            for ext in ("db", "sqlite", "sqlite3"):
+                db_files.extend(config_dir.glob("*.{}".format(ext)))
+            self.files += tuple(str(f) for f in db_files)
         if (
             config_dir
             and (config_dir / "inspect-data.json").exists()
diff --git a/docs/settings.rst b/docs/settings.rst
index 8437fb04..a6d50543 100644
--- a/docs/settings.rst
+++ b/docs/settings.rst
@@ -46,7 +46,7 @@ Datasette will detect the files in that directory and automatically configure it
 
 The files that can be included in this directory are as follows. All are optional.
 
-* ``*.db`` - SQLite database files that will be served by Datasette
+* ``*.db`` (or ``*.sqlite3`` or ``*.sqlite``) - SQLite database files that will be served by Datasette
 * ``metadata.json`` - :ref:`metadata` for those databases - ``metadata.yaml`` or ``metadata.yml`` can be used as well
 * ``inspect-data.json`` - the result of running ``datasette inspect *.db --inspect-file=inspect-data.json`` from the configuration directory - any database files listed here will be treated as immutable, so they should not be changed while Datasette is running
 * ``settings.json`` - settings that would normally be passed using ``--setting`` - here they should be stored as a JSON object of key/value pairs
diff --git a/tests/test_config_dir.py b/tests/test_config_dir.py
index f5ecf0d6..c2af3836 100644
--- a/tests/test_config_dir.py
+++ b/tests/test_config_dir.py
@@ -49,7 +49,7 @@ def config_dir(tmp_path_factory):
     (config_dir / "metadata.json").write_text(json.dumps(METADATA), "utf-8")
     (config_dir / "settings.json").write_text(json.dumps(SETTINGS), "utf-8")
 
-    for dbname in ("demo.db", "immutable.db"):
+    for dbname in ("demo.db", "immutable.db", "j.sqlite3", "k.sqlite"):
         db = sqlite3.connect(str(config_dir / dbname))
         db.executescript(
             """
@@ -151,12 +151,11 @@ def test_databases(config_dir_client):
     response = config_dir_client.get("/-/databases.json")
     assert 200 == response.status
     databases = response.json
-    assert 2 == len(databases)
+    assert 4 == len(databases)
     databases.sort(key=lambda d: d["name"])
-    assert "demo" == databases[0]["name"]
-    assert databases[0]["is_mutable"]
-    assert "immutable" == databases[1]["name"]
-    assert not databases[1]["is_mutable"]
+    for db, expected_name in zip(databases, ("demo", "immutable", "j", "k")):
+        assert expected_name == db["name"]
+        assert db["is_mutable"] == (expected_name != "immutable")
 
 
 @pytest.mark.parametrize("filename", ("metadata.yml", "metadata.yaml"))