diff --git a/aiohttp/client.py b/aiohttp/client.py
index bc6c0aaaa5d..79d33d6128a 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -611,6 +611,11 @@ async def _request(
                         with suppress(LookupError):
                             proxy, proxy_auth = get_env_proxy_for_url(url)
 
+                    if proxy and not "http" in proxy.scheme:
+                        raise ValueError(
+                            "aiohttp works with http(s) proxy only currently."
+                        )
+
                     req = self._request_class(
                         method,
                         url,
diff --git a/tests/test_client_request.py b/tests/test_client_request.py
index 1b5d3a88fff..b7b4ec06b35 100644
--- a/tests/test_client_request.py
+++ b/tests/test_client_request.py
@@ -1570,3 +1570,10 @@ def test_request_info_tuple_new() -> None:
         ).real_url
         is url
     )
+
+
+def test_hostname_err(make_request: _RequestMaker) -> None:
+    with pytest.raises(ValueError):
+        make_request("get", "http://python.org/", proxy="socks5://127.0.0.1:80")
+    with pytest.raises(ValueError):
+        make_request("get", "http://python.org/", proxy="socks5h://127.0.0.1:80")