diff --git a/Project.toml b/Project.toml
index dfd4def..1115466 100644
--- a/Project.toml
+++ b/Project.toml
@@ -9,6 +9,6 @@ MutableArithmetics = "d8a4904e-b15c-11e9-3269-09a3773c0cb0"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 
 [compat]
-MutableArithmetics = "1.4.3"
+MutableArithmetics = "1.4.5"
 SparseArrays = "1"
 julia = "1.6"
diff --git a/src/coefficients.jl b/src/coefficients.jl
index 02f40db..87c93fc 100644
--- a/src/coefficients.jl
+++ b/src/coefficients.jl
@@ -117,10 +117,6 @@ function LinearAlgebra.dot(ac::AbstractCoefficients, w::AbstractVector)
     end
 end
 
-# general mutable API
-# why here?
-MA.operate!(::typeof(zero), v::SparseVector) = (v .= 0; v)
-
 Base.zero(X::AbstractCoefficients) = MA.operate!(zero, similar(X))
 Base.:-(X::AbstractCoefficients) = MA.operate_to!(__prealloc(X, -1, *), -, X)
 Base.:*(a::Number, X::AbstractCoefficients) = X * a
diff --git a/test/group_algebra.jl b/test/group_algebra.jl
index 6804b6b..0fcc41c 100644
--- a/test/group_algebra.jl
+++ b/test/group_algebra.jl
@@ -184,7 +184,7 @@
 
                     @test P2 * P3 == P3 * P2 == P
 
-                    @test_broken -RG(h) == (-1) * RG(h)
+                    @test -RG(h) == (-1) * RG(h)
                     @test !iszero(RG(1) - RG(h))
 
                     P2m = (RG(1) - RG(h)) // 2