diff --git a/src/coefficients.jl b/src/coefficients.jl
index 9330350..a2b0d6c 100644
--- a/src/coefficients.jl
+++ b/src/coefficients.jl
@@ -33,6 +33,7 @@ key_type(b) = keytype(b)
 # back to `keytype{::Type{<:AbstractArray})` which returns `Int`.
 key_type(::Type{SparseArrays.SparseVector{V,K}}) where {V,K} = K
 key_type(v::SparseArrays.SparseVector) = key_type(typeof(v))
+key_type(::Tuple) = Int
 
 Base.iszero(ac::AbstractCoefficients) = isempty(keys(ac))
 
@@ -260,5 +261,3 @@ function MA.operate_to!(
     end
     return res
 end
-
-
diff --git a/src/types.jl b/src/types.jl
index e3bd5bf..7ec2dce 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -51,9 +51,12 @@ function MA.promote_operation(::typeof(basis), ::Type{<:AlgebraElement{A}}) wher
 end
 basis(a::AlgebraElement) = basis(parent(a))
 
+value_type(coeffs) = valtype(coeffs)
+value_type(::NTuple{N,T}) where {N,T} = T
+
 function AlgebraElement(coeffs, A::AbstractStarAlgebra)
     _sanity_checks(coeffs, A)
-    return AlgebraElement{typeof(A),valtype(coeffs),typeof(coeffs)}(coeffs, A)
+    return AlgebraElement{typeof(A),value_type(coeffs),typeof(coeffs)}(coeffs, A)
 end
 
 function AlgebraElement(