diff --git a/mercurial/sshpeer.py b/mercurial/sshpeer.py
--- a/mercurial/sshpeer.py
+++ b/mercurial/sshpeer.py
@@ -140,6 +140,10 @@
     def close(self):
         return self._main.close()
 
+    @property
+    def closed(self):
+        return self._main.closed
+
     def flush(self):
         return self._main.flush()
 
diff --git a/tests/test-check-interfaces.py b/tests/test-check-interfaces.py
--- a/tests/test-check-interfaces.py
+++ b/tests/test-check-interfaces.py
@@ -113,6 +113,10 @@
     def close(self):
         pass
 
+    @property
+    def closed(self):
+        pass
+
 
 def main():
     ui = uimod.ui()