diff --git a/vllm/entrypoints/openai/rpc/server.py b/vllm/entrypoints/openai/rpc/server.py
index 7a72a6f732c99..60bb23b9bde05 100644
--- a/vllm/entrypoints/openai/rpc/server.py
+++ b/vllm/entrypoints/openai/rpc/server.py
@@ -30,7 +30,9 @@ def __init__(self, async_engine_args: AsyncEngineArgs,
 
         # Init socket for readiness state.
         self.socket = self.context.socket(zmq.constants.ROUTER)
-        self.socket.bind(f"tcp://localhost:{port}")
+        # Note numeric form of localhost should be used for zmq bind(),
+        # see https://stackoverflow.com/a/8958414
+        self.socket.bind(f"tcp://127.0.0.1:{port}")
 
     def cleanup(self):
         """Cleanup all resources."""