diff --git a/base/channels.jl b/base/channels.jl
index aa4d913dcdadd..07f1975bcee81 100644
--- a/base/channels.jl
+++ b/base/channels.jl
@@ -183,7 +183,7 @@ Close a channel. An exception (optionally given by `excp`), is thrown by:
 * [`put!`](@ref) on a closed channel.
 * [`take!`](@ref) and [`fetch`](@ref) on an empty, closed channel.
 """
-function close(c::Channel, excp::Exception=closed_exception())
+function close(c::Channel, @nospecialize(excp::Exception=closed_exception()))
     lock(c)
     try
         c.excp = excp