diff --git a/CHANGELOG.md b/CHANGELOG.md
index 830fc1d7da..4f662f2deb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,8 @@
   ([#6819](https://github.com/mitmproxy/mitmproxy/pull/6819), @mhils)
 * Set the `unbuffered` (stdout/stderr) flag for the `mitmdump` PyInstaller build.
   ([#6821](https://github.com/mitmproxy/mitmproxy/pull/6821), @Prinzhorn)
+* Fix a bug where client replay would not work with proxyauth.
+  ([#6866](https://github.com/mitmproxy/mitmproxy/pull/6866), @mhils)
 
 
 ## 17 April 2024: mitmproxy 10.3.0
diff --git a/mitmproxy/addons/proxyauth.py b/mitmproxy/addons/proxyauth.py
index 13e1ef02e2..9250251da3 100644
--- a/mitmproxy/addons/proxyauth.py
+++ b/mitmproxy/addons/proxyauth.py
@@ -76,6 +76,8 @@ def requestheaders(self, f: http.HTTPFlow) -> None:
             # Is this connection authenticated by a previous HTTP CONNECT?
             if f.client_conn in self.authenticated:
                 f.metadata["proxyauth"] = self.authenticated[f.client_conn]
+            elif f.is_replay:
+                pass
             else:
                 self.authenticate_http(f)
 
diff --git a/test/mitmproxy/addons/test_proxyauth.py b/test/mitmproxy/addons/test_proxyauth.py
index 743bc635bf..e715e9d11d 100644
--- a/test/mitmproxy/addons/test_proxyauth.py
+++ b/test/mitmproxy/addons/test_proxyauth.py
@@ -239,6 +239,11 @@ def test_handlers(self):
             assert not f2.response
             assert f2.metadata["proxyauth"] == ("test", "test")
 
+            f3 = tflow.tflow()
+            f3.is_replay = True
+            up.requestheaders(f3)
+            assert not f2.response
+
 
 @pytest.mark.parametrize(
     "spec",