diff --git a/base/dSFMT.jl b/base/dSFMT.jl
index b78b1b1931c7b..b0eb6e7d41089 100644
--- a/base/dSFMT.jl
+++ b/base/dSFMT.jl
@@ -2,6 +2,8 @@
 
 module dSFMT
 
+import Base: copy, copy!, ==
+
 export DSFMT_state, dsfmt_get_min_array_size, dsfmt_get_idstring,
        dsfmt_init_gen_rand, dsfmt_init_by_array, dsfmt_gv_init_by_array,
        dsfmt_fill_array_close_open!, dsfmt_fill_array_close1_open2!,
@@ -21,10 +23,16 @@ const JPOLY1e21  = "e172e20c5d2de26b567c0cace9e7c6cc4407bd5ffcd22ca59d37b73d54fd
 
 type DSFMT_state
     val::Vector{Int32}
-    DSFMT_state() = new(Array{Int32}(JN32))
-    DSFMT_state(val::Vector{Int32}) = new(val)
+
+    DSFMT_state(val::Vector{Int32} = zeros(Int32, JN32)) =
+        new(length(val) == JN32 ? val : throw(DomainError()))
 end
 
+copy!(dst::DSFMT_state, src::DSFMT_state) = (copy!(dst.val, src.val); dst)
+copy(src::DSFMT_state) = DSFMT_state(copy(src.val))
+
+==(s1::DSFMT_state, s2::DSFMT_state) = s1.val == s2.val
+
 function dsfmt_get_idstring()
     idstring = ccall((:dsfmt_get_idstring,:libdSFMT),
                      Ptr{UInt8},
diff --git a/base/random.jl b/base/random.jl
index c14fd9a96b389..b8e8c90d0a220 100644
--- a/base/random.jl
+++ b/base/random.jl
@@ -4,7 +4,7 @@ module Random
 
 using Base.dSFMT
 using Base.GMP: GMP_VERSION, Limb
-import Base.copymutable
+import Base: copymutable, copy, copy!, ==
 
 export srand,
        rand, rand!,
@@ -64,16 +64,37 @@ rand(rng::RandomDevice, ::Type{CloseOpen}) = rand(rng, Close1Open2) - 1.0
 const MTCacheLength = dsfmt_get_min_array_size()
 
 type MersenneTwister <: AbstractRNG
+    seed::Vector{UInt32}
     state::DSFMT_state
     vals::Vector{Float64}
     idx::Int
-    seed::Vector{UInt32}
 
-    MersenneTwister(state::DSFMT_state, seed) = new(state, Array{Float64}(MTCacheLength), MTCacheLength, seed)
-    MersenneTwister(seed) = srand(new(DSFMT_state(), Array{Float64}(MTCacheLength)), seed)
-    MersenneTwister() = MersenneTwister(0)
+    function MersenneTwister(seed, state, vals, idx)
+        length(vals) == MTCacheLength &&  0 <= idx <= MTCacheLength || throw(DomainError())
+        new(seed, state, vals, idx)
+    end
+end
+
+MersenneTwister(seed::Vector{UInt32}, state::DSFMT_state) =
+    MersenneTwister(seed, state, zeros(Float64, MTCacheLength), MTCacheLength)
+
+MersenneTwister(seed=0) = srand(MersenneTwister(Vector{UInt32}(), DSFMT_state()), seed)
+
+function copy!(dst::MersenneTwister, src::MersenneTwister)
+    copy!(resize!(dst.seed, length(src.seed)), src.seed)
+    copy!(dst.state, src.state)
+    copy!(dst.vals, src.vals)
+    dst.idx = src.idx
+    dst
 end
 
+copy(src::MersenneTwister) =
+    MersenneTwister(copy(src.seed), copy(src.state), copy(src.vals), src.idx)
+
+==(r1::MersenneTwister, r2::MersenneTwister) =
+    r1.seed == r2.seed && r1.state == r2.state && isequal(r1.vals, r2.vals) && r1.idx == r2.idx
+
+
 ## Low level API for MersenneTwister
 
 @inline mt_avail(r::MersenneTwister) = MTCacheLength - r.idx
@@ -105,7 +126,7 @@ end
 @inline rand_ui2x52_raw(r::MersenneTwister) = rand_ui52_raw(r) % UInt128 << 64 | rand_ui52_raw(r)
 
 function srand(r::MersenneTwister, seed::Vector{UInt32})
-    r.seed = seed
+    copy!(resize!(r.seed, length(seed)), seed)
     dsfmt_init_by_array(r.state, r.seed)
     mt_setempty!(r)
     return r
@@ -117,7 +138,7 @@ function randjump(mt::MersenneTwister, jumps::Integer, jumppoly::AbstractString)
     push!(mts, mt)
     for i in 1:jumps-1
         cmt = mts[end]
-        push!(mts, MersenneTwister(dSFMT.dsfmt_jump(cmt.state, jumppoly),  cmt.seed))
+        push!(mts, MersenneTwister(cmt.seed, dSFMT.dsfmt_jump(cmt.state, jumppoly)))
     end
     return mts
 end
diff --git a/test/random.jl b/test/random.jl
index 8ec79ef76d2f2..91358626f5601 100644
--- a/test/random.jl
+++ b/test/random.jl
@@ -414,3 +414,33 @@ end
 # test that the following is not an error (#16925)
 srand(typemax(UInt))
 srand(typemax(UInt128))
+
+# copy and ==
+let seed = rand(UInt32, 10)
+    r = MersenneTwister(seed)
+    @test r == MersenneTwister(seed) # r.vals should be all zeros
+    s = copy(r)
+    @test s == r && s !== r
+    skip, len = rand(0:2000, 2)
+    for j=1:skip
+        rand(r)
+        rand(s)
+    end
+    @test rand(r, len) == rand(s, len)
+    @test s == r
+end
+
+# MersenneTwister initialization with invalid values
+@test_throws DomainError Base.dSFMT.DSFMT_state(zeros(Int32, rand(0:Base.dSFMT.JN32-1)))
+@test_throws DomainError MersenneTwister(zeros(UInt32, 1), Base.dSFMT.DSFMT_state(),
+                                         zeros(Float64, 10), 0)
+@test_throws DomainError MersenneTwister(zeros(UInt32, 1), Base.dSFMT.DSFMT_state(),
+                                         zeros(Float64, Base.Random.MTCacheLength), -1)
+
+# seed is private to MersenneTwister
+let seed = rand(UInt32, 10)
+    r = MersenneTwister(seed)
+    @test r.seed == seed && r.seed !== seed
+    resize!(seed, 4)
+    @test r.seed != seed
+end