diff --git a/CHANGES/4125.feature b/CHANGES/4125.feature
new file mode 100644
index 00000000000..43dd2638b4f
--- /dev/null
+++ b/CHANGES/4125.feature
@@ -0,0 +1 @@
+Use `Iterable` hint instead of `Sequence` for `Application` `middleware` parameter.
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index d126b74eb47..f28a8f9eaee 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -223,6 +223,7 @@ Simon Kennedy
 Sin-Woo Bang
 Stanislas Plum
 Stanislav Prokop
+Stefan Tjarks
 Stepan Pletnev
 Stephen Granade
 Steven Seguin
diff --git a/aiohttp/web_app.py b/aiohttp/web_app.py
index a70ff506fd0..f668feeae4b 100644
--- a/aiohttp/web_app.py
+++ b/aiohttp/web_app.py
@@ -75,7 +75,7 @@ class Application(MutableMapping[str, Any]):
 
     def __init__(self, *,
                  logger: logging.Logger=web_logger,
-                 middlewares: Sequence[_Middleware]=(),
+                 middlewares: Iterable[_Middleware]=(),
                  handler_args: Mapping[str, Any]=None,
                  client_max_size: int=1024**2,
                  debug: Any=...  # mypy doesn't support ellipsis