diff --git a/Project.toml b/Project.toml
index 90de204..1002b26 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,13 +1,17 @@
 name = "StarAlgebras"
 uuid = "0c0c59c1-dc5f-42e9-9a8b-b5dc384a6cd1"
 authors = ["Marek Kaluba <kalmar@mailbox.org>"]
-version = "0.2.0"
+version = "0.2.1"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 
 [compat]
+Groups = "0.8"
+GroupsCore = "0.5"
+PermutationGroups = "0.6"
+SparseArrays = "1"
 julia = "1.6"
 
 [extras]
diff --git a/src/arithmetic.jl b/src/arithmetic.jl
index 376638a..40c1450 100644
--- a/src/arithmetic.jl
+++ b/src/arithmetic.jl
@@ -1,6 +1,10 @@
 # module structure:
-Base.:*(a::Number, X::AlgebraElement) =
-    mul!(similar(X, promote_type(eltype(X), typeof(a))), X, a)
+
+function Base.:*(a::Number, X::AlgebraElement)
+    T = Base._return_type(*, Tuple{eltype(X),typeof(a)})
+    return mul!(similar(X, T), X, a)
+end
+
 Base.:*(X::AlgebraElement, a::Number) = a * X
 Base.:(/)(X::AlgebraElement, a::Number) = inv(a) * X
 
diff --git a/src/show.jl b/src/show.jl
index 1ae427e..82301ed 100644
--- a/src/show.jl
+++ b/src/show.jl
@@ -1,7 +1,7 @@
-Base.show(io::IO, A::AbstractStarAlgebra) =
-    print(io, "*-algebra of $(object(A))")
-Base.show(io::IO, ::Type{<:StarAlgebra{O,T}}) where {O,T} =
-    print(io, "StarAlgebra{$O, $T, …}")
+function Base.show(io::IO, A::AbstractStarAlgebra)
+    ioc = IOContext(io, :limit => true, :compact => true)
+    return print(ioc, "*-algebra of ", object(A))
+end
 
 __prints_with_minus(::Any) = false
 __prints_with_minus(x::Real) = x < 0
diff --git a/test/arithmetic.jl b/test/arithmetic.jl
index 24fe89e..19b71e9 100644
--- a/test/arithmetic.jl
+++ b/test/arithmetic.jl
@@ -1,21 +1,10 @@
-using GroupsCore
-using PermutationGroups
-import Random
-
-StarAlgebras.star(g::PermutationGroups.GroupElement) = inv(g)
-
-using SparseArrays
-if VERSION < v"1.9"
-    Base.sum(v::SparseVector) = sum(nonzeros(v))
-end
-
 @testset "Arithmetic" begin
     G = PermGroup(perm"(1,2,3)", perm"(1,2)")
     b = StarAlgebras.Basis{UInt8}(collect(G))
     l = length(b)
     RG = StarAlgebra(G, b, (l, l))
 
-    @test contains(sprint(show, RG), "*-algebra of Permutation group")
+    @test contains(sprint(show, RG), "*-algebra of")
 
     @testset "Module structure" begin
         a = AlgebraElement(ones(Int, order(G)), RG)
@@ -114,7 +103,7 @@ end
 
         @test supp(z) == StarAlgebras.basis(parent(z))
         @test supp(RG(1) + RG(g)) == [one(G), g]
-        @test supp(a) == [one(G), h, g]
+        @test supp(a) == [one(G), g, h]
 
         @testset "Projections in star algebras" begin
             b = StarAlgebras.basis(RG)
diff --git a/test/runtests.jl b/test/runtests.jl
index 01cb81c..4781da1 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -8,7 +8,18 @@ include("test_example_words.jl")
 @testset "StarAlgebras" begin
     include("mtables.jl")
     include("constructors.jl")
+
+    using GroupsCore
+    StarAlgebras.star(g::GroupsCore.GroupElement) = inv(g)
+
+    using SparseArrays
+    if VERSION < v"1.9"
+        Base.sum(v::SparseVector) = sum(nonzeros(v))
+    end
+
+    using PermutationGroups
     include("arithmetic.jl")
 
+    using Groups
     include("sum_of_squares.jl")
 end
diff --git a/test/sum_of_squares.jl b/test/sum_of_squares.jl
index 80ef114..bfba90e 100644
--- a/test/sum_of_squares.jl
+++ b/test/sum_of_squares.jl
@@ -1,7 +1,4 @@
-using Groups
-
 @testset "sum of squares in FreeGroup *-algebra" begin
-      StarAlgebras.star(g::Groups.GroupElement) = inv(g)
       F = Groups.FreeGroup(4)
       S = [Groups.gens(F); inv.(Groups.gens(F))]
 
diff --git a/test/test_example_words.jl b/test/test_example_words.jl
index fc327ce..276a20e 100644
--- a/test/test_example_words.jl
+++ b/test/test_example_words.jl
@@ -29,18 +29,13 @@ function Base.:*(w::Word, z::Word)
 end
 
 function StarAlgebras.star(w::Word)
-    newletters = similar(w.letters)
-
     # star(:a) = :b
     # star(:b) = :a
     # star(:c) = :c
 
     star_d = Dict(1 => 2, 2 => 1)
 
-    for (i, l) in enumerate(Iterators.reverse(w.letters))
-        k = haskey(star_d, l) ? star_d[l] : l
-        newletters[i] = k
-    end
+    newletters = [get(star_d, l, l) for l in Iterators.reverse(w.letters)]
     return Word(w.alphabet, newletters)
 end