diff --git a/src/mstructures.jl b/src/mstructures.jl
index 41267fd..88fb870 100644
--- a/src/mstructures.jl
+++ b/src/mstructures.jl
@@ -28,6 +28,10 @@ When the product is not representable faithfully,
 """
 abstract type MultiplicativeStructure end
 
+struct UnsafeAddMul{M<:MultiplicativeStructure}
+    structure::M
+end
+
 function MA.operate_to!(
     res::SparseCoefficients,
     ms::MultiplicativeStructure,
@@ -35,20 +39,20 @@ function MA.operate_to!(
     w::AbstractCoefficients,
 )
     MA.operate!(zero, res)
-    res = fmac!(ms, res, v, w)
+    res = MA.operate_to!(res, UnsafeAddMul(ms), v, w)
     __canonicalize!(res)
     return res
 end
 
-function fmac!(
-    ms::MultiplicativeStructure,
+function MA.operate_to!(
     res::SparseCoefficients,
+    ms::UnsafeAddMul,
     v::AbstractCoefficients,
     w::AbstractCoefficients,
 )
     for (kv, a) in pairs(v)
         for (kw, b) in pairs(w)
-            c = ms(kv, kw) # ::AbstractCoefficients
+            c = ms.structure(kv, kw) # ::AbstractCoefficients
             unsafe_append!(res, c => a * b)
         end
     end
@@ -61,8 +65,12 @@ function MA.operate_to!(
     X::AbstractVector,
     Y::AbstractVector,
 )
-    res = (res === X || res === Y) ? zero(res) : (res .= zero(eltype(res)))
-    fmac!(ms, res, X, Y)
+    if res === X || res === Y
+        res = zero(res)
+    else
+        MA.operate!(zero, res)
+    end
+    MA.operate_to!(res, UnsafeAddMul(ms), X, Y)
     res = __canonicalize!(res)
     return res
 end
diff --git a/src/mtables.jl b/src/mtables.jl
index b470847..e3359e4 100644
--- a/src/mtables.jl
+++ b/src/mtables.jl
@@ -81,9 +81,9 @@ function complete!(mt::MTable)
     return mt
 end
 
-function fmac!(
-    ms::MTable,
+function MA.operate_to!(
     res::AbstractSparseVector,
+    ms::UnsafeAddMul{<:MTable},
     v::AbstractVector,
     w::AbstractVector,
 )
@@ -93,9 +93,9 @@ function fmac!(
 
     for (kv, a) in _nzpairs(v)
         for (kw, b) in _nzpairs(w)
-            c = ms(kv, kw)
+            c = ms.structure(kv, kw)
             for (k, v) in pairs(c)
-                push!(idcs, ms[k])
+                push!(idcs, ms.structure[k])
                 push!(vals, v * a * b)
             end
         end