diff --git a/src/managers.jl b/src/managers.jl
index f888b0a1ceeac9..1b48bc85375077 100644
--- a/src/managers.jl
+++ b/src/managers.jl
@@ -373,7 +373,7 @@ manage
 struct DefaultClusterManager <: ClusterManager
 end
 
-const tunnel_hosts_map = Dict{AbstractString, Semaphore}()
+const tunnel_hosts_map = Dict{String, Semaphore}()
 
 """
     connect(manager::ClusterManager, pid::Int, config::WorkerConfig) -> (instrm::IO, outstrm::IO)