diff --git a/Project.toml b/Project.toml
index d9acf6a..3b50d0d 100644
--- a/Project.toml
+++ b/Project.toml
@@ -4,19 +4,19 @@ authors = ["Marek Kaluba <kalmar@amu.edu.pl>"]
 version = "0.7.2"
 
 [deps]
+Folds = "41a02a25-b8f0-4f67-bc48-60067656b558"
 GroupsCore = "d5909c97-4eac-4ecc-a3dc-fdd0858a4120"
 KnuthBendix = "c2604015-7b3d-4a30-8a26-9074551ec60a"
 OrderedCollections = "bac558e1-5e72-5ebc-8fee-abe8a469f55d"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
-ThreadsX = "ac1d9e8a-700a-412c-b207-f0111f4b6c0d"
 
 [compat]
 AbstractAlgebra = "0.22"
+Folds = "0.2.7"
 GroupsCore = "0.4"
 KnuthBendix = "0.3"
 OrderedCollections = "1"
 PermutationGroups = "0.3"
-ThreadsX = "0.1"
 julia = "1.3"
 
 [extras]
diff --git a/src/Groups.jl b/src/Groups.jl
index c662566..cc7ec85 100644
--- a/src/Groups.jl
+++ b/src/Groups.jl
@@ -1,7 +1,7 @@
 module Groups
 
 using GroupsCore
-using ThreadsX
+using Folds
 import KnuthBendix
 import KnuthBendix: AbstractWord, Alphabet, Word
 import KnuthBendix: alphabet
diff --git a/src/wl_ball.jl b/src/wl_ball.jl
index ebb370c..69fce79 100644
--- a/src/wl_ball.jl
+++ b/src/wl_ball.jl
@@ -8,14 +8,14 @@ radius and multiplication operation to be used.
 """
 function wlmetric_ball_serial(S::AbstractVector{T}, center::T=one(first(S)); radius = 2, op = *) where {T}
     @assert radius >= 1
-    old = unique!([center, [center*s for s in S]...])
+    old = union!([center], [center*s for s in S])
     return _wlmetric_ball(S, old, radius, op, collect, unique!)
 end
 
 function wlmetric_ball_thr(S::AbstractVector{T}, center::T=one(first(S)); radius = 2, op = *) where {T}
     @assert radius >= 1
-    old = unique!([center, [center*s for s in S]...])
-    return _wlmetric_ball(S, old, radius, op, ThreadsX.collect, ThreadsX.unique)
+    old = union!([center], [center*s for s in S])
+    return _wlmetric_ball(S, old, radius, op, Folds.collect, Folds.unique)
 end
 
 function _wlmetric_ball(S, old, radius, op, collect, unique)