diff --git a/test/caching_allocations.jl b/test/caching_allocations.jl
index cab2114..4742af5 100644
--- a/test/caching_allocations.jl
+++ b/test/caching_allocations.jl
@@ -61,7 +61,12 @@ end
         YY = deepcopy(Y)
         _alloc_test(YY, *, Y, Y, 25)
         _alloc_test(YY, +, Y, Y, 0)
-        # SparseArrays calls `Base.unalias` which allocates
+        @test_broken 1 == 2 # it's actually the one below:
+        # [2] operate_to!(output::SparseVector{Float64, Int64}, op::typeof(-), args::SparseVector{Float64, Int64})
+        #   @ MutableArithmetics ~/.julia/packages/MutableArithmetics/iovKe/src/interface.jl:391
+        # _alloc_test(YY, -, Y, Y, 0)
+
+        # SparseArrays calls `Base.unalias` which allocates:
         _alloc_test(YY, +, YY, Y, 2)
         _alloc_test(YY, +, Y, YY, 2)
     end