diff --git a/REQUIRE b/REQUIRE
index 137767a42..918dea87c 100644
--- a/REQUIRE
+++ b/REQUIRE
@@ -1 +1,2 @@
 julia 0.6
+Compat 0.40
diff --git a/src/DataStructures.jl b/src/DataStructures.jl
index a17ebc5ca..22e69ce20 100644
--- a/src/DataStructures.jl
+++ b/src/DataStructures.jl
@@ -16,6 +16,13 @@ module DataStructures
                  union, intersect, symdiff, setdiff, issubset,
                  find, searchsortedfirst, searchsortedlast, endof, in
 
+    import Compat.uninitialized
+    @static if !isdefined(Base, :KeySet) # https://github.com/JuliaLang/julia/pull/24580
+        const KeySet{K,T<:Associative{K}} = Base.KeyIterator{T}
+    else
+        import Base.KeySet
+    end
+
     export Deque, Stack, Queue, CircularDeque
     export deque, enqueue!, dequeue!, dequeue_pair!, update!, reverse_iter
     export capacity, num_blocks, front, back, top, top_with_handle, sizehint!
@@ -52,7 +59,11 @@ module DataStructures
 
     import Base: eachindex, keytype, valtype
 
-    _include_string(str) = eval(parse(str))
+    @static if VERSION < v"0.7.0-DEV.2437"
+        _include_string(str) = eval(parse(str))
+    else
+        _include_string(str) = eval(Meta.parse(str))
+    end
 
     include("delegate.jl")
 
@@ -106,13 +117,13 @@ module DataStructures
     # Remove when Julia 0.7 (or whatever version is after v0.6) is released
     @deprecate DefaultDictBase(default, ks::AbstractArray, vs::AbstractArray) DefaultDictBase(default, zip(ks, vs))
     @deprecate DefaultDictBase(default, ks, vs) DefaultDictBase(default, zip(ks, vs))
-    @deprecate DefaultDictBase{K,V}(::Type{K}, ::Type{V}, default) DefaultDictBase{K,V}(default)
+    @deprecate DefaultDictBase(::Type{K}, ::Type{V}, default) where {K,V} DefaultDictBase{K,V}(default)
 
     @deprecate DefaultDict(default, ks, vs) DefaultDict(default, zip(ks, vs))
-    @deprecate DefaultDict{K,V}(::Type{K}, ::Type{V}, default) DefaultDict{K,V}(default)
+    @deprecate DefaultDict(::Type{K}, ::Type{V}, default) where {K,V} DefaultDict{K,V}(default)
 
     @deprecate DefaultOrderedDict(default, ks, vs) DefaultOrderedDict(default, zip(ks, vs))
-    @deprecate DefaultOrderedDict{K,V}(::Type{K}, ::Type{V}, default) DefaultOrderedDict{K,V}(default)
+    @deprecate DefaultOrderedDict(::Type{K}, ::Type{V}, default) where {K,V} DefaultOrderedDict{K,V}(default)
 
     function SortedMultiDict(ks::AbstractVector{K},
                              vs::AbstractVector{V},
@@ -124,10 +135,10 @@ module DataStructures
         SortedMultiDict(o, zip(ks,vs))
     end
 
-    @deprecate PriorityQueue{K,V}(::Type{K}, ::Type{V}) PriorityQueue{K,V}()    
-    @deprecate PriorityQueue{K,V}(::Type{K}, ::Type{V}, o::Ordering) PriorityQueue{K,V,typeof(o)}(o)    
+    @deprecate PriorityQueue(::Type{K}, ::Type{V}) where {K,V} PriorityQueue{K,V}()
+    @deprecate PriorityQueue(::Type{K}, ::Type{V}, o::Ordering) where {K,V} PriorityQueue{K,V,typeof(o)}(o)
     @deprecate (PriorityQueue{K,V,ForwardOrdering}() where {K,V}) PriorityQueue{K,V}()
-    
+
     function PriorityQueue(ks::AbstractVector{K},
                            vs::AbstractVector{V},
                            o::Ordering=Forward) where {K,V}
@@ -137,5 +148,5 @@ module DataStructures
         end
         PriorityQueue(o, zip(ks,vs))
     end
-                                            
+
 end
diff --git a/src/balanced_tree.jl b/src/balanced_tree.jl
index 18811efa3..b43c25a35 100644
--- a/src/balanced_tree.jl
+++ b/src/balanced_tree.jl
@@ -125,15 +125,15 @@ mutable struct BalancedTree23{K, D, Ord <: Ordering}
     deletionchild::Array{Int,1}
     deletionleftkey::Array{K,1}
     function BalancedTree23{K,D,Ord}(ord1::Ord) where {K,D,Ord<:Ordering}
-        tree1 = Vector{TreeNode{K}}(1)
+        tree1 = Vector{TreeNode{K}}(uninitialized, 1)
         initializeTree!(tree1)
-        data1 = Vector{KDRec{K,D}}(2)
+        data1 = Vector{KDRec{K,D}}(uninitialized, 2)
         initializeData!(data1)
         u1 = IntSet()
         push!(u1, 1, 2)
-        new{K,D,Ord}(ord1, data1, tree1, 1, 1, Vector{Int}(0), Vector{Int}(0),
+        new{K,D,Ord}(ord1, data1, tree1, 1, 1, Vector{Int}(), Vector{Int}(),
                      u1,
-                     Vector{Int}(3), Vector{K}(3))
+                     Vector{Int}(uninitialized, 3), Vector{K}(uninitialized, 3))
     end
 end
 
@@ -243,8 +243,8 @@ function empty!(t::BalancedTree23)
     initializeTree!(t.tree)
     t.depth = 1
     t.rootloc = 1
-    t.freetreeinds = Vector{Int}(0)
-    t.freedatainds = Vector{Int}(0)
+    t.freetreeinds = Vector{Int}()
+    t.freedatainds = Vector{Int}()
     empty!(t.useddatacells)
     push!(t.useddatacells, 1, 2)
     nothing
diff --git a/src/circ_deque.jl b/src/circ_deque.jl
index deb48b629..131d66989 100644
--- a/src/circ_deque.jl
+++ b/src/circ_deque.jl
@@ -11,7 +11,7 @@ mutable struct CircularDeque{T}
     last::Int
 end
 
-CircularDeque{T}(n::Int) where {T} = CircularDeque(Vector{T}(n), n, 0, 1, n)
+CircularDeque{T}(n::Int) where {T} = CircularDeque(Vector{T}(uninitialized, n), n, 0, 1, n)
 
 Base.length(D::CircularDeque) = D.n
 Base.eltype(::Type{CircularDeque{T}}) where {T} = T
diff --git a/src/classified_collections.jl b/src/classified_collections.jl
index 0c1eea6a0..a41a6ae43 100644
--- a/src/classified_collections.jl
+++ b/src/classified_collections.jl
@@ -16,7 +16,7 @@ classified_lists(K::Type, V::Type) = ClassifiedCollections(K, Vector{V})
 classified_sets(K::Type, V::Type) = ClassifiedCollections(K, Set{V})
 classified_counters(K::Type, T::Type) = ClassifiedCollections(K, Accumulator{T, Int})
 
-_create_empty(::Type{Vector{T}}) where {T} = Vector{T}(0)
+_create_empty(::Type{Vector{T}}) where {T} = Vector{T}()
 _create_empty(::Type{Set{T}}) where {T} = Set{T}()
 _create_empty(::Type{Accumulator{T,V}}) where {T,V} = Accumulator(T, V)
 
diff --git a/src/default_dict.jl b/src/default_dict.jl
index 8d33d176f..7fdda9fe9 100644
--- a/src/default_dict.jl
+++ b/src/default_dict.jl
@@ -58,8 +58,8 @@ DefaultDictBase{K,V}(default::F) where {K,V,F} = DefaultDictBase{K,V,F,Dict{K,V}
 @delegate_return_parent DefaultDictBase.d [ delete!, empty!, setindex!, sizehint! ]
 
 similar(d::DefaultDictBase{K,V,F}) where {K,V,F} = DefaultDictBase{K,V,F}(d.default)
-in(key, v::Base.KeyIterator{T}) where {T<:DefaultDictBase} = key in keys(v.dict.d)
-next(v::Base.KeyIterator{T}, i) where {T<:DefaultDictBase} = (v.dict.d.keys[i], Base.skip_deleted(v.dict.d,i+1))
+in(key, v::KeySet{<:Any,T}) where {T<:DefaultDictBase} = key in keys(v.dict.d)
+next(v::KeySet{<:Any,T}, i) where {T<:DefaultDictBase} = (v.dict.d.keys[i], Base.skip_deleted(v.dict.d,i+1))
 next(v::Base.ValueIterator{T}, i) where {T<:DefaultDictBase} = (v.dict.d.vals[i], Base.skip_deleted(v.dict.d,i+1))
 
 getindex(d::DefaultDictBase, key) = get!(d.d, key, d.default)
@@ -138,7 +138,7 @@ for _Dict in [:Dict, :OrderedDict]
         push!(d::$DefaultDict, p, q, r...) = push!(push!(push!(d, p), q), r...)
 
         similar(d::$DefaultDict{K,V,F}) where {K,V,F} = $DefaultDict{K,V,F}(d.d.default)
-        in(key, v::Base.KeyIterator{T}) where {T<:$DefaultDict} = key in keys(v.dict.d.d)
+        in(key, v::KeySet{<:Any,T}) where {T<:$DefaultDict} = key in keys(v.dict.d.d)
     end
 end
 
@@ -182,4 +182,4 @@ isordered(::Type{T}) where {T<:DefaultOrderedDict} = true
 # @delegate_return_parent DefaultSortedDict.d [ delete!, empty!, setindex!, sizehint! ]
 
 # similar{K,V,F}(d::DefaultSortedDict{K,V,F}) = DefaultSortedDict{K,V,F}(d.d.default)
-# in{T<:DefaultSortedDict}(key, v::Base.KeyIterator{T}) = key in keys(v.dict.d.d)
+# in{T<:DefaultSortedDict}(key, v::KeySet{<:Any,T}) = key in keys(v.dict.d.d)
diff --git a/src/delegate.jl b/src/delegate.jl
index 08a66d160..274dbc47b 100644
--- a/src/delegate.jl
+++ b/src/delegate.jl
@@ -14,7 +14,7 @@ macro delegate(source, targets)
     fieldname = unquote(source.args[2])
     funcnames = targets.args
     n = length(funcnames)
-    fdefs = Vector{Any}(n)
+    fdefs = Vector{Any}(uninitialized, n)
     for i in 1:n
         funcname = esc(funcnames[i])
         fdefs[i] = quote
@@ -30,7 +30,7 @@ macro delegate_return_parent(source, targets)
     fieldname = unquote(source.args[2])
     funcnames = targets.args
     n = length(funcnames)
-    fdefs = Vector{Any}(n)
+    fdefs = Vector{Any}(uninitialized, n)
     for i in 1:n
         funcname = esc(funcnames[i])
         fdefs[i] = quote
diff --git a/src/deque.jl b/src/deque.jl
index 34673dade..b974f26a7 100644
--- a/src/deque.jl
+++ b/src/deque.jl
@@ -14,7 +14,7 @@ mutable struct DequeBlock{T}
     next::DequeBlock{T}  # ref to next block
 
     function DequeBlock{T}(capa::Int, front::Int) where T
-        data = Vector{T}(capa)
+        data = Vector{T}(uninitialized, capa)
         blk = new{T}(data, capa, front, front-1)
         blk.prev = blk
         blk.next = blk
diff --git a/src/heaps.jl b/src/heaps.jl
index a89e04cb6..c56410d78 100644
--- a/src/heaps.jl
+++ b/src/heaps.jl
@@ -71,7 +71,7 @@ include("heaps/arrays_as_heaps.jl")
 
 function extract_all!(h::AbstractHeap{VT}) where VT
     n = length(h)
-    r = Vector{VT}(n)
+    r = Vector{VT}(uninitialized, n)
     for i = 1 : n
         r[i] = pop!(h)
     end
@@ -80,7 +80,7 @@ end
 
 function extract_all_rev!(h::AbstractHeap{VT}) where VT
     n = length(h)
-    r = Vector{VT}(n)
+    r = Vector{VT}(uninitialized, n)
     for i = 1 : n
         r[n + 1 - i] = pop!(h)
     end
diff --git a/src/heaps/binary_heap.jl b/src/heaps/binary_heap.jl
index 7bd4db321..baad627f1 100644
--- a/src/heaps/binary_heap.jl
+++ b/src/heaps/binary_heap.jl
@@ -107,7 +107,7 @@ mutable struct BinaryHeap{T,Comp} <: AbstractHeap{T}
     valtree::Vector{T}
 
     function BinaryHeap{T,Comp}(comp::Comp) where {T,Comp}
-        new{T,Comp}(comp, Vector{T}(0))
+        new{T,Comp}(comp, Vector{T}())
     end
 
     function BinaryHeap{T,Comp}(comp::Comp, xs) where {T,Comp}  # xs is an iterable collection of values
diff --git a/src/heaps/mutable_binary_heap.jl b/src/heaps/mutable_binary_heap.jl
index e158466ec..cbb77addb 100644
--- a/src/heaps/mutable_binary_heap.jl
+++ b/src/heaps/mutable_binary_heap.jl
@@ -127,8 +127,8 @@ function _make_mutable_binary_heap(comp::Comp, ty::Type{T}, values) where {Comp,
     # make a static binary index tree from a list of values
 
     n = length(values)
-    nodes = Vector{MutableBinaryHeapNode{T}}(n)
-    nodemap = Vector{Int}(n)
+    nodes = Vector{MutableBinaryHeapNode{T}}(uninitialized, n)
+    nodemap = Vector{Int}(uninitialized, n)
 
     i::Int = 0
     for v in values
@@ -156,8 +156,8 @@ mutable struct MutableBinaryHeap{VT, Comp} <: AbstractMutableHeap{VT,Int}
     node_map::Vector{Int}
 
     function MutableBinaryHeap{VT, Comp}(comp::Comp) where {VT, Comp}
-        nodes = Vector{MutableBinaryHeapNode{VT}}(0)
-        node_map = Vector{Int}(0)
+        nodes = Vector{MutableBinaryHeapNode{VT}}()
+        node_map = Vector{Int}()
         new{VT, Comp}(comp, nodes, node_map)
     end
 
diff --git a/src/int_set.jl b/src/int_set.jl
index cc597b12a..f73dbdc70 100644
--- a/src/int_set.jl
+++ b/src/int_set.jl
@@ -14,7 +14,7 @@ end
 mutable struct IntSet
     bits::BitVector
     inverse::Bool
-    IntSet() = new(fill!(BitVector(256), false), false)
+    IntSet() = new(falses(256), false)
 end
 IntSet(itr) = union!(IntSet(), itr)
 
@@ -63,7 +63,7 @@ function _matchlength!(b::BitArray, newlen::Integer)
     len = length(b)
     len > newlen && return splice!(b, newlen+1:len)
     len < newlen && _resize0!(b, newlen)
-    return BitVector(0)
+    return BitVector()
 end
 
 const _intset_bounds_err_msg = "elements of IntSet must be between 0 and typemax(Int)-1"
diff --git a/src/ordered_dict.jl b/src/ordered_dict.jl
index 034dd78c5..cb6bd3a12 100644
--- a/src/ordered_dict.jl
+++ b/src/ordered_dict.jl
@@ -4,7 +4,7 @@ import Base: haskey, get, get!, getkey, delete!, push!, pop!, empty!,
              setindex!, getindex, length, isempty, start,
              next, done, keys, values, setdiff, setdiff!,
              union, union!, intersect, filter, filter!,
-             hash, eltype, KeyIterator, ValueIterator, convert, copy,
+             hash, eltype, ValueIterator, convert, copy,
              merge
 
 """
@@ -21,7 +21,7 @@ mutable struct OrderedDict{K,V} <: Associative{K,V}
     dirty::Bool
 
     function OrderedDict{K,V}() where {K,V}
-        new{K,V}(zeros(Int32,16), Vector{K}(0), Vector{V}(0), 0, false)
+        new{K,V}(zeros(Int32,16), Vector{K}(), Vector{V}(), 0, false)
     end
     function OrderedDict{K,V}(kv) where {K,V}
         h = OrderedDict{K,V}()
@@ -56,8 +56,8 @@ copy(d::OrderedDict) = OrderedDict(d)
 # OrderedDict{K,V}(kv::Tuple{Vararg{Tuple{K,V}}})          = OrderedDict{K,V}(kv)
 # OrderedDict{K  }(kv::Tuple{Vararg{Tuple{K,Any}}})        = OrderedDict{K,Any}(kv)
 # OrderedDict{V  }(kv::Tuple{Vararg{Tuple{Any,V}}})        = OrderedDict{Any,V}(kv)
-_oldOrderedDict1 = "OrderedDict{V}(kv::Tuple{Vararg{Pair{TypeVar(:K),V}}}) = OrderedDict{Any,V}(kv)"
-_newOrderedDict1 = "OrderedDict{V}(kv::Tuple{Vararg{Pair{K,V} where K}})   = OrderedDict{Any,V}(kv)"
+_oldOrderedDict1 = "OrderedDict(kv::Tuple{Vararg{Pair{TypeVar(:K),V}}}) where {V} = OrderedDict{Any,V}(kv)"
+_newOrderedDict1 = "OrderedDict(kv::Tuple{Vararg{Pair{K,V} where K}}) where {V}   = OrderedDict{Any,V}(kv)"
 OrderedDict(kv::Tuple{Vararg{Pair{K,V}}}) where {K,V}         = OrderedDict{K,V}(kv)
 OrderedDict(kv::Tuple{Vararg{Pair{K}}}) where {K}             = OrderedDict{K,Any}(kv)
 VERSION < v"0.6.0-dev.2123" ? _include_string(_oldOrderedDict1) : _include_string(_newOrderedDict1)
@@ -67,8 +67,8 @@ OrderedDict(kv::AbstractArray{Tuple{K,V}}) where {K,V} = OrderedDict{K,V}(kv)
 OrderedDict(kv::AbstractArray{Pair{K,V}}) where {K,V}  = OrderedDict{K,V}(kv)
 OrderedDict(kv::Associative{K,V}) where {K,V}          = OrderedDict{K,V}(kv)
 
-_oldOrderedDict2 = "OrderedDict{V}(ps::Pair{TypeVar(:K),V}...,) = OrderedDict{Any,V}(ps)"
-_newOrderedDict2 = "OrderedDict{V}(ps::(Pair{K,V} where K)...,) = OrderedDict{Any,V}(ps)"
+_oldOrderedDict2 = "OrderedDict(ps::Pair{TypeVar(:K),V}...,) where {V} = OrderedDict{Any,V}(ps)"
+_newOrderedDict2 = "OrderedDict(ps::(Pair{K,V} where K)...,) where {V} = OrderedDict{Any,V}(ps)"
 OrderedDict(ps::Pair{K,V}...) where {K,V}          = OrderedDict{K,V}(ps)
 OrderedDict(ps::Pair{K}...,) where {K}             = OrderedDict{K,Any}(ps)
 VERSION < v"0.6.0-dev.2123" ? _include_string(_oldOrderedDict2) : _include_string(_newOrderedDict2)
@@ -376,7 +376,7 @@ function get(default::Base.Callable, h::OrderedDict{K,V}, key) where {K,V}
 end
 
 haskey(h::OrderedDict, key) = (ht_keyindex(h, key, true) >= 0)
-in(key, v::KeyIterator{T}) where {T<:OrderedDict} = (ht_keyindex(v.dict, key, true) >= 0)
+in(key, v::KeySet{<:Any,T}) where {T<:OrderedDict} = (ht_keyindex(v.dict, key, true) >= 0)
 
 function getkey(h::OrderedDict{K,V}, key, default) where {K,V}
     index = ht_keyindex(h, key, true)
@@ -429,7 +429,7 @@ end
 done(t::OrderedDict, i) = done(t.keys, i)
 next(t::OrderedDict, i) = (Pair(t.keys[i],t.vals[i]), i+1)
 
-next(v::KeyIterator{T}, i) where {T<:OrderedDict} = (v.dict.keys[i], i+1)
+next(v::KeySet{<:Any,T}, i) where {T<:OrderedDict} = (v.dict.keys[i], i+1)
 next(v::ValueIterator{T}, i) where {T<:OrderedDict} = (v.dict.vals[i], i+1)
 
 function merge(d::OrderedDict, others::Associative...)
diff --git a/src/priorityqueue.jl b/src/priorityqueue.jl
index 0f553365f..f17b8c8af 100644
--- a/src/priorityqueue.jl
+++ b/src/priorityqueue.jl
@@ -32,11 +32,11 @@ mutable struct PriorityQueue{K,V,O<:Ordering} <: Associative{K,V}
     index::Dict{K, Int}
 
     function PriorityQueue{K,V,O}(o::O) where {K,V,O<:Ordering}
-        new{K,V,O}(Vector{Pair{K,V}}(0), o, Dict{K, Int}())
+        new{K,V,O}(Vector{Pair{K,V}}(), o, Dict{K, Int}())
     end
 
     function PriorityQueue{K,V,O}(o::O, itr) where {K,V,O<:Ordering}
-        xs = Vector{Pair{K,V}}(length(itr))
+        xs = Vector{Pair{K,V}}(uninitialized, length(itr))
         index = Dict{K, Int}()
         for (i, (k, v)) in enumerate(itr)
             xs[i] = Pair{K,V}(k, v)
@@ -225,7 +225,7 @@ function enqueue!(pq::PriorityQueue{K,V}, pair::Pair{K,V}) where {K,V}
     push!(pq.xs, pair)
     pq.index[key] = length(pq)
     percolate_up!(pq, length(pq))
-    
+
     return pq
 end
 
diff --git a/test/runtests.jl b/test/runtests.jl
index 8b0e5dcd5..deae3ad1e 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,7 +1,7 @@
-using Base.Test
+using Compat.Test
 using DataStructures
 const IntSet = DataStructures.IntSet
-using Primes
+using Primes, Compat
 
 @test isempty(detect_ambiguities(Base, Core, DataStructures))
 
diff --git a/test/test_mutable_binheap.jl b/test/test_mutable_binheap.jl
index 4c5c18266..430db0243 100644
--- a/test/test_mutable_binheap.jl
+++ b/test/test_mutable_binheap.jl
@@ -6,7 +6,7 @@ function heap_values(h::MutableBinaryHeap{VT,Comp}) where {VT,Comp}
     n = length(h)
     nodes = h.nodes
     @assert length(nodes) == n
-    vs = Vector{VT}(n)
+    vs = Vector{VT}(uninitialized, n)
     for i = 1 : n
         vs[i] = nodes[i].value
     end
@@ -17,7 +17,7 @@ function list_values(h::MutableBinaryHeap{VT,Comp}) where {VT,Comp}
     n = length(h)
     nodes = h.nodes
     nodemap = h.node_map
-    vs = Vector{VT}(0)
+    vs = Vector{VT}()
     for i = 1 : length(nodemap)
         id = nodemap[i]
         if id > 0
diff --git a/test/test_ordered_dict.jl b/test/test_ordered_dict.jl
index 771e70520..e33e94092 100644
--- a/test/test_ordered_dict.jl
+++ b/test/test_ordered_dict.jl
@@ -129,7 +129,7 @@
 
     let _d = OrderedDict([("a", 0)])
         v = [k for k in filter(x->length(x)==1, collect(keys(_d)))]
-        @test isa(v, Vector{String}) || isa(v, Vector{ASCIIString})
+        @test isa(v, Vector{String})
     end
 
     let d = OrderedDict(((1, 2), (3, 4))),
diff --git a/test/test_ordered_set.jl b/test/test_ordered_set.jl
index 7856fe967..639c346b1 100644
--- a/test/test_ordered_set.jl
+++ b/test/test_ordered_set.jl
@@ -136,9 +136,9 @@
 
     # find
     s = OrderedSet([1,3,5,7])
-    @test findfirst(s,1) == 1
-    @test findfirst(s,7) == 4
-    @test findfirst(s,2) == 0
+    @test findfirst(equalto(1), s) == 1
+    @test findfirst(equalto(7), s) == 4
+    @test findfirst(equalto(2), s) == 0
 
     # setdiff
     @test isequal(setdiff(OrderedSet([1,2,3]), OrderedSet()),        OrderedSet([1,2,3]))
diff --git a/test/test_priority_queue.jl b/test/test_priority_queue.jl
index e435612d7..8c8e7f068 100644
--- a/test/test_priority_queue.jl
+++ b/test/test_priority_queue.jl
@@ -14,7 +14,7 @@ function test_issorted!(pq::PriorityQueue, priorities, rev=false)
             @test priorities[last] <= priorities[value]
         else
             @test priorities[value] <= priorities[last]
-        end            
+        end
         value = last
     end
 end
@@ -87,7 +87,7 @@ end
 
     pq11 = PriorityQueue(Pair{Char}['a'=>1,'b'=>2])
     @test peek(pq11) == ('a'=>1)
-    
+
     # duplicate key => ArgumentError
     @test_throws ArgumentError PriorityQueue('a'=>1, 'a'=>2)
 
@@ -95,7 +95,7 @@ end
     @test_throws ArgumentError PriorityQueue(['a'])
     @test_throws ArgumentError PriorityQueue(Reverse, ['a'])
     @test_throws ArgumentError PriorityQueue{Char,Int}(Base.Order.Reverse, ['a'])
-    
+
     # Silly test
     @test_throws ArgumentError PriorityQueue(Reverse, Reverse)
 
@@ -139,7 +139,7 @@ end
         enqueue!(pq, kv)
     end
     test_issorted!(pq, priorities)
-    
+
     # enqueing values via enqueue!
     pq = PriorityQueue()
     for (k, v) in priorities
@@ -199,7 +199,7 @@ end
     xs = heapify(10:-1:1)
     @test issorted([heappop!(xs) for _ in 1:10])
 
-    xs = Vector{Int}(0)
+    xs = Vector{Int}()
     for priority in values(priorities)
         heappush!(xs, priority)
     end
diff --git a/test/test_sorted_containers.jl b/test/test_sorted_containers.jl
index ee22dfc5f..72527b374 100644
--- a/test/test_sorted_containers.jl
+++ b/test/test_sorted_containers.jl
@@ -96,10 +96,10 @@ function checkcorrectness(t::DataStructures.BalancedTree23{K,D,Ord},
     dsz = size(t.data, 1)
     tsz = size(t.tree, 1)
     r = t.rootloc
-    bfstreenodes = Vector{Int}(0)
+    bfstreenodes = Vector{Int}()
     tdpth = t.depth
     intree = IntSet()
-    levstart = Vector{Int}(tdpth)
+    levstart = Vector{Int}(uninitialized, tdpth)
     push!(bfstreenodes, r)
     levstart[1] = 1
     push!(intree, r)
@@ -132,8 +132,8 @@ function checkcorrectness(t::DataStructures.BalancedTree23{K,D,Ord},
     end
     bfstreesize = size(bfstreenodes, 1)
     dataused = IntSet()
-    minkeys = Vector{K}(bfstreesize)
-    maxkeys = Vector{K}(bfstreesize)
+    minkeys = Vector{K}(uninitialized, bfstreesize)
+    maxkeys = Vector{K}(uninitialized, bfstreesize)
     for s = levstart[tdpth] : bfstreesize
         anc = bfstreenodes[s]
         c1 = t.tree[anc].child1