diff --git a/base/io.jl b/base/io.jl
index ca653d8970dd9b..817c1bcaad7a30 100644
--- a/base/io.jl
+++ b/base/io.jl
@@ -129,6 +129,7 @@ function read!(s::IO, a::Vector{UInt8})
     for i in 1:length(a)
         a[i] = read(s, UInt8)
     end
+    return a
 end
 
 function read!{T}(s::IO, a::Array{T})
diff --git a/test/core.jl b/test/core.jl
index 6fabf8c54076a4..435fe6e0bff45a 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -3401,3 +3401,8 @@ b8932 = Vec3_8932(2,2,2)
 f13261() = (x = (error("oops"),); +(x...))
 g13261() = f13261()
 @test_throws ErrorException g13261()
+
+#13433, read!(::IO, a::Vector{UInt8}) should return a
+type IO13433 <: IO end
+Base.read(::IO13433, ::Type{UInt8}) = 0x01
+@test read!(IO13433(), Array(UInt8, 4)) == [0x01, 0x01, 0x01, 0x01]