diff --git a/base/show.jl b/base/show.jl
index 300acd186e14b..e77e2b9735317 100644
--- a/base/show.jl
+++ b/base/show.jl
@@ -340,7 +340,7 @@ getindex(io::IO, key) = throw(KeyError(key))
 get(io::IOContext, key, default) = get(io.dict, key, default)
 get(io::IO, key, default) = default
 
-displaysize(io::IOContext) = haskey(io, :displaysize) ? io[:displaysize] : displaysize(io.io)
+displaysize(io::IOContext) = haskey(io, :displaysize) ? io[:displaysize]::Tuple{Int,Int} : displaysize(io.io)
 
 show_circular(io::IO, @nospecialize(x)) = false
 function show_circular(io::IOContext, @nospecialize(x))