diff --git a/src/managers.jl b/src/managers.jl
index fccc5ea..c16a1f0 100644
--- a/src/managers.jl
+++ b/src/managers.jl
@@ -606,7 +606,7 @@ function connect(manager::ClusterManager, pid::Int, config::WorkerConfig)
 
     # master connecting to workers
     if config.io !== nothing
-        (bind_addr, port::Int) = read_worker_host_port(config.io)
+        (bind_addr, port::Int) = read_worker_host_port(config.io::IO)
         pubhost = something(config.host, bind_addr)
         config.host = pubhost
         config.port = port