diff --git a/datasette/utils/asgi.py b/datasette/utils/asgi.py
index 2d4a6cf..5a6fa68 100644
--- a/datasette/utils/asgi.py
+++ b/datasette/utils/asgi.py
@@ -160,9 +160,20 @@ class Request:
         qs = self.query_string
         return "{}{}".format(self.path, ("?" + qs) if qs else "")
 
+    # Parsed query string, cached against the query string it was parsed from
+    _args_query_string = None
+    _parsed_args = None
+
     @property
     def args(self):
-        return MultiParams(parse_qs(qs=self.query_string, keep_blank_values=True))
+        query_string = self.query_string
+        if query_string != self._args_query_string:
+            self._parsed_args = parse_qs(qs=query_string, keep_blank_values=True)
+            self._args_query_string = query_string
+        # Copy the lists, so callers cannot modify the cached values
+        return MultiParams(
+            {key: list(values) for key, values in self._parsed_args.items()}
+        )
 
     @property
     def actor(self):
diff --git a/tests/test_internals_request.py b/tests/test_internals_request.py
index 91ef368..7382f24 100644
--- a/tests/test_internals_request.py
+++ b/tests/test_internals_request.py
@@ -327,6 +327,18 @@ def test_request_blank_values():
     assert request.args._data == {"a": ["b"], "foo": ["bar", "bar2"], "baz": [""]}
 
 
+def test_request_args_follow_scope_changes():
+    request = Request.fake("/?a=1&a=2")
+    # Modifying the returned lists does not affect later lookups
+    request.args.getlist("a").append("3")
+    assert request.args.getlist("a") == ["1", "2"]
+    # Replacing request.scope, or modifying it in place
+    request.scope = dict(request.scope, query_string=b"b=3")
+    assert request.args._data == {"b": ["3"]}
+    request.scope["query_string"] = b"c=4"
+    assert request.args._data == {"c": ["4"]}
+
+
 def test_json_in_query_string_name():
     query_string = (
         '?_through.["roadside_attraction_characteristics"%2C"characteristic_id"]=1'