diff --git a/src/AMD.jl b/src/AMD.jl
index 2bfb445..8e2a7c0 100644
--- a/src/AMD.jl
+++ b/src/AMD.jl
@@ -106,7 +106,9 @@ function print(io :: IO, meta :: Amd)
   print(io, s)
 end
 
-for (validfn, typ) in ((:_amd_valid, Cint), (:_amd_l_valid, Clong))
+_Clong = Base.Sys.WORD_SIZE == 32 ? Clong : Clonglong
+
+for (validfn, typ) in ((:_amd_valid, Cint), (:_amd_l_valid, _Clong))
 
   @eval begin
 
@@ -123,7 +125,7 @@ for (validfn, typ) in ((:_amd_valid, Cint), (:_amd_l_valid, Clong))
 end
 
 
-for (orderfn, typ) in ((:_amd_order, Cint), (:_amd_l_order, Clong))
+for (orderfn, typ) in ((:_amd_order, Cint), (:_amd_l_order, _Clong))
 
   @eval begin
 
@@ -145,7 +147,7 @@ for (orderfn, typ) in ((:_amd_order, Cint), (:_amd_l_order, Clong))
   end
 end
 
-function amd{F,T<:Union{Cint,Clong}}(A :: SparseMatrixCSC{F,T})
+function amd{F,T<:Union{Cint,_Clong}}(A :: SparseMatrixCSC{F,T})
   meta = Amd()
   amd(A, meta)
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index a875567..b070073 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,9 +1,10 @@
 using AMD
 using Base.Test
 
+_Clong = Base.Sys.WORD_SIZE == 32 ? Clong : Clonglong
 for n in [10, 20, 30]
   for density in [.25, .75, 1.0]
-    for T in [Cint, Clong]
+    for T in [Cint, _Clong]
       A = convert(SparseMatrixCSC{Float64,T}, sprand(n, n, density))
       @assert amd_valid(A)
 
@@ -21,7 +22,7 @@ end
 
 # For coverage.
 meta = Amd()
-A = convert(SparseMatrixCSC{Float64,Clong}, sprand(10, 10, .5))
+A = convert(SparseMatrixCSC{Float64,_Clong}, sprand(10, 10, .5))
 p = amd(A, meta)
 show(meta)
 print(meta)