diff --git a/src/arithmetic.jl b/src/arithmetic.jl
index 46e7134..96256ef 100644
--- a/src/arithmetic.jl
+++ b/src/arithmetic.jl
@@ -86,17 +86,17 @@ end
 function MP.substitute(
     s::MP.AbstractSubstitutionType,
     p::_AE,
-    args::MP.AbstractSubstitution...,
+    args::MP.Substitutions,
 )
-    return MP.substitute(s, MP.polynomial(p), args...)
+    return MP.substitute(s, MP.polynomial(p), args)
 end
 
 function MP.subs(p::_AE, args::MP.AbstractSubstitution...)
-    return MP.substitute(MP.Subs(), p, args...)
+    return MP.substitute(MP.Subs(), p, args)
 end
 
 function (p::_AE)(args::MP.AbstractSubstitution...)
-    return MP.substitute(MP.Eval(), p, args...)
+    return MP.substitute(MP.Eval(), p, args)
 end
 
 function (p::_AE)(x::NTuple{N,<:Number}) where {N}
@@ -109,6 +109,6 @@ end
 
 (p::_AE)(x::Number...) = (MP.polynomial(p))(x...)
 
-function MP.differentiate(p::_AE, args...)
-    return MP.differentiate(MP.polynomial(p), args...)
+function MP.differentiate(p::_AE, x)
+    return MP.differentiate(MP.polynomial(p), x)
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index 52ccdb5..e411565 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -112,7 +112,9 @@ function api_test(B::Type{<:MB.AbstractMonomialIndexed}, degree)
     @test const_alg_el(ones(length(x))...) == const_mono
     @test const_alg_el(tuple(ones(length(x))...)) == const_mono
     @test subs(const_alg_el, x => ones(length(x))) == const_mono
+    @test const_alg_el(x[1] => x[2], x[2] => x[1]) == const_mono
     @test differentiate(const_alg_el, x) == differentiate(const_mono, x)
+    @test differentiate(const_alg_el, x, 2) == differentiate(const_mono, x, 2)
 end
 
 function univ_orthogonal_test(