diff --git a/base/boot.jl b/base/boot.jl
index 8ca6d392ead671..f8ed86b0fb6b7c 100644
--- a/base/boot.jl
+++ b/base/boot.jl
@@ -969,6 +969,7 @@ arrayset(inbounds::Bool, A::Array{T}, x::Any, i::Int...) where {T} = Main.Base.s
 arraysize(a::Array) = a.size
 arraysize(a::Array, i::Int) = sle_int(i, nfields(a.size)) ? getfield(a.size, i) : 1
 export arrayref, arrayset, arraysize, const_arrayref
+const check_top_bit = check_sign_bit
 
 # For convenience
 EnterNode(old::EnterNode, new_dest::Int) = isdefined(old, :scope) ?