diff --git a/datasette/app.py b/datasette/app.py
index dfba438a..6ea208e6 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -422,6 +422,7 @@ class Datasette:
                 "full": sys.version,
             },
             "datasette": datasette_version,
+            "asgi": "3.0",
             "sqlite": {
                 "version": sqlite_version,
                 "fts_versions": fts_versions,
diff --git a/tests/test_api.py b/tests/test_api.py
index 3655ed42..6ed990f3 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -1197,6 +1197,7 @@ def test_plugins_json(app_client):
 def test_versions_json(app_client):
     response = app_client.get("/-/versions.json")
     assert "python" in response.json
+    assert "3.0" == response.json.get("asgi")
     assert "version" in response.json["python"]
     assert "full" in response.json["python"]
     assert "datasette" in response.json