diff --git a/src/DataArrays.jl b/src/DataArrays.jl
index b4e317b..25e0a06 100644
--- a/src/DataArrays.jl
+++ b/src/DataArrays.jl
@@ -38,7 +38,6 @@ module DataArrays
            padNA,
            pdata,
            percent_change,
-           Perm,
            PooledDataArray,
            PooledDataMatrix,
            PooledDataVecs,
diff --git a/src/grouping.jl b/src/grouping.jl
index c5199cb..3d8875d 100644
--- a/src/grouping.jl
+++ b/src/grouping.jl
@@ -1,4 +1,4 @@
-function groupsort_indexer(x::AbstractVector, ngroups::Integer)
+function groupsort_indexer(x::AbstractVector, ngroups::Integer, nalast::Bool=false)
     # translated from Wes McKinney's groupsort_indexer in pandas (file: src/groupby.pyx).
 
     # count group sizes, location 0 for NA
@@ -11,10 +11,17 @@ function groupsort_indexer(x::AbstractVector, ngroups::Integer)
 
     # mark the start of each contiguous group of like-indexed data
     where = fill(1, ngroups + 1)
-    for i = 2:ngroups+1
-        where[i] = where[i - 1] + counts[i - 1]
+    if nalast
+        for i = 3:ngroups+1
+            where[i] = where[i - 1] + counts[i - 1]
+        end
+        where[1] = where[end] + counts[end]
+    else
+        for i = 2:ngroups+1
+            where[i] = where[i - 1] + counts[i - 1]
+        end
     end
-    
+
     # this is our indexer
     result = fill(0, n)
     for i = 1:n
@@ -25,4 +32,4 @@ function groupsort_indexer(x::AbstractVector, ngroups::Integer)
     result, where, counts
 end
 
-groupsort_indexer(pv::PooledDataVector) = groupsort_indexer(pv.refs, length(pv.pool))
+groupsort_indexer(pv::PooledDataVector, nalast::Bool=false) = groupsort_indexer(pv.refs, length(pv.pool), nalast)
diff --git a/src/pooleddataarray.jl b/src/pooleddataarray.jl
index c263558..24f6ebd 100644
--- a/src/pooleddataarray.jl
+++ b/src/pooleddataarray.jl
@@ -773,19 +773,24 @@ end
 ##
 ##############################################################################
 
-# TODO handle sortperm for non-sorted keys
-Base.sortperm(pda::PooledDataArray) = groupsort_indexer(pda)[1]
-function Base.sortperm(pda::PooledDataArray)
-    if issorted(pda.pool)
-        return groupsort_indexer(pda)[1]
-    else
-        return sortperm(reorder!(copy(pda)))
+function Base.sortperm(pda::PooledDataArray; alg::Base.Sort.Algorithm=Base.Sort.DEFAULT_UNSTABLE,
+                       lt::Function=isless, by::Function=identity,
+                       rev::Bool=false, order=Base.Sort.Forward)
+    order = Base.ord(lt, by, rev, order)
+
+    # TODO handle custom ordering efficiently
+    if !isa(order, Base.Order.ForwardOrdering) && !isa(order, Base.Order.ReverseOrdering)
+        return sort!([1:length(pda)], alg, Base.Order.Perm(order,pda))
     end
+
+    # TODO handle non-sorted keys without copying
+    perm = issorted(pda.pool) ? groupsort_indexer(pda, true)[1] : sortperm(reorder(pda))
+    isa(order, Base.Order.ReverseOrdering) && reverse!(perm)
+    perm
 end
 
-Base.sortperm(pda::PooledDataArray, ::Base.Sort.ReverseOrdering) = reverse(sortperm(pda))
-Base.sort(pda::PooledDataArray) = pda[sortperm(pda)]
-Base.sort(pda::PooledDataArray, ::Base.Sort.ReverseOrdering) = pda[reverse(sortperm(pda))]
+Base.sort(pda::PooledDataArray; kw...) = pda[sortperm(pda; kw...)]
+
 type FastPerm{O<:Base.Sort.Ordering,V<:AbstractVector} <: Base.Sort.Ordering
     ord::O
     vec::V
diff --git a/test/sort.jl b/test/sort.jl
index 4fa01f7..f4dbb23 100644
--- a/test/sort.jl
+++ b/test/sort.jl
@@ -1,6 +1,16 @@
 module TestSort
 using DataArrays, Base.Test
 
+dv1 = @data([9, 1, 8, NA, 3, 3, 7, NA])
+dv2 = 1.0 * dv1
+dv3 = DataArray([1:8])
+pdv1 = convert(PooledDataArray, dv1)
+
+@test sortperm(dv1) == sortperm(dv2)
+@test sortperm(dv1) == sortperm(pdv1)
+@test isequal(sort(dv1), convert(DataArray, sort(dv1)))
+@test isequal(sort(dv1), convert(DataArray, sort(pdv1)))
+
 for T in (Float64, BigFloat)
     n = 1000
     na = randbool(n)
@@ -8,10 +18,12 @@ for T in (Float64, BigFloat)
     a = Array(T, n)
     ra = randn(n-nna)
     a[!na] = ra
-    da = DataArray(a, na)
-    @test isequal(sort(da), [DataArray(sort(dropna(da))), DataArray(T, nna)])
-    @test isequal(da[sortperm(da)], [DataArray(sort(dropna(da))), DataArray(T, nna)])
-    @test isequal(sort(da, rev=true), [DataArray(T, nna), DataArray(sort(dropna(da), rev=true))])
-    @test isequal(da[sortperm(da, rev=true)], [DataArray(T, nna), DataArray(sort(dropna(da), rev=true))])
+    for da in (DataArray(a, na), PooledDataArray(a, na), (pda = PooledDataArray(a, na); setlevels!(pda, shuffle!(pda.pool))))
+        @test isequal(sort(da), [DataArray(sort(dropna(da))), DataArray(T, nna)])
+        @test isequal(sort(da; lt=(x,y)->isless(x,y)), [DataArray(sort(dropna(da))), DataArray(T, nna)])
+        @test isequal(da[sortperm(da)], [DataArray(sort(dropna(da))), DataArray(T, nna)])
+        @test isequal(sort(da, rev=true), [DataArray(T, nna), DataArray(sort(dropna(da), rev=true))])
+        @test isequal(da[sortperm(da, rev=true)], [DataArray(T, nna), DataArray(sort(dropna(da), rev=true))])
+    end
+end
 end
-end
\ No newline at end of file