diff --git a/app.py b/app.py
index 2634d85..a0b60c6 100644
--- a/app.py
+++ b/app.py
@@ -26,6 +26,9 @@ app.url_map.converters['regex'] = flask_util.RegexConverter
 app.after_request(flask_util.default_modern_headers)
 app.register_error_handler(Exception, flask_util.handle_exception)
 
+# don't redirect API requests with blank path elements
+app.url_map.redirect_defaults = True
+
 app.wsgi_app = handlers.ndb_context_middleware(
     app.wsgi_app, client=appengine_config.ndb_client)
 
diff --git a/redirect.py b/redirect.py
index 462cae4..5fc5c1f 100644
--- a/redirect.py
+++ b/redirect.py
@@ -31,7 +31,7 @@ CACHE_TIME = datetime.timedelta(seconds=15)
 @app.get(r'/r/<path:to>')
 @cache.cached(timeout=CACHE_TIME.total_seconds(), query_string=True,
               response_filter=flask_util.not_5xx)
-def redir(to=None):
+def redir(to):
     """301 redirect to the embedded fully qualified URL.
 
     e.g. redirects /r/https://foo.com/bar?baz to https://foo.com/bar?baz