diff --git a/base/set.jl b/base/set.jl
index e6831bfaf4fe6..df98cb43174ab 100644
--- a/base/set.jl
+++ b/base/set.jl
@@ -133,19 +133,28 @@ function unique(itr)
     end
     x, i = next(itr, i)
     if !isleaftype(T)
-        T = typeof(x)
-        out = Vector{T}()
-        seen = Set{T}()
+        S = typeof(x)
+        return _unique_from(itr, S[x], Set{S}((x,)), i)
     end
     push!(seen, x)
     push!(out, x)
+    return unique_from(itr, out, seen, i)
+end
+
+_unique_from(itr, out, seen, i) = unique_from(itr, out, seen, i)
+@inline function unique_from{T}(itr, out::Vector{T}, seen, i)
     while !done(itr, i)
         x, i = next(itr, i)
         S = typeof(x)
         if !(S === T || S <: T)
-            T = typejoin(S, T)
-            seen = convert(Set{T}, seen)
-            out = convert(Vector{T}, out)
+            R = typejoin(S, T)
+            seenR = convert(Set{R}, seen)
+            outR = convert(Vector{R}, out)
+            if !in(x, seenR)
+                push!(seenR, x)
+                push!(outR, x)
+            end
+            return _unique_from(itr, outR, seenR, i)
         end
         if !in(x, seen)
             push!(seen, x)