diff --git a/ext/QuantumToolboxCUDAExt.jl b/ext/QuantumToolboxCUDAExt.jl
index b4fcf0fc2..11a764244 100644
--- a/ext/QuantumToolboxCUDAExt.jl
+++ b/ext/QuantumToolboxCUDAExt.jl
@@ -2,7 +2,7 @@ module QuantumToolboxCUDAExt
 
 using QuantumToolbox
 using QuantumToolbox: makeVal, getVal
-import QuantumToolbox: _sparse_similar
+import QuantumToolbox: _sparse_similar, _convert_eltype_wordsize
 import CUDA: cu, CuArray, allowscalar
 import CUDA.CUSPARSE: CuSparseVector, CuSparseMatrixCSC, CuSparseMatrixCSR, AbstractCuSparseArray
 import SparseArrays: SparseVector, SparseMatrixCSC
@@ -81,27 +81,20 @@ function cu(A::QuantumObject; word_size::Union{Val,Int} = Val(64))
 
     return cu(A, makeVal(word_size))
 end
-cu(A::QuantumObject, word_size::Union{Val{32},Val{64}}) = CuArray{_change_eltype(eltype(A), word_size)}(A)
+cu(A::QuantumObject, word_size::Union{Val{32},Val{64}}) = CuArray{_convert_eltype_wordsize(eltype(A), word_size)}(A)
 function cu(
     A::QuantumObject{ObjType,DimsType,<:SparseVector},
     word_size::Union{Val{32},Val{64}},
 ) where {ObjType<:QuantumObjectType,DimsType<:AbstractDimensions}
-    return CuSparseVector{_change_eltype(eltype(A), word_size)}(A)
+    return CuSparseVector{_convert_eltype_wordsize(eltype(A), word_size)}(A)
 end
 function cu(
     A::QuantumObject{ObjType,DimsType,<:SparseMatrixCSC},
     word_size::Union{Val{32},Val{64}},
 ) where {ObjType<:QuantumObjectType,DimsType<:AbstractDimensions}
-    return CuSparseMatrixCSC{_change_eltype(eltype(A), word_size)}(A)
+    return CuSparseMatrixCSC{_convert_eltype_wordsize(eltype(A), word_size)}(A)
 end
 
-_change_eltype(::Type{T}, ::Val{64}) where {T<:Int} = Int64
-_change_eltype(::Type{T}, ::Val{32}) where {T<:Int} = Int32
-_change_eltype(::Type{T}, ::Val{64}) where {T<:AbstractFloat} = Float64
-_change_eltype(::Type{T}, ::Val{32}) where {T<:AbstractFloat} = Float32
-_change_eltype(::Type{Complex{T}}, ::Val{64}) where {T<:Union{Int,AbstractFloat}} = ComplexF64
-_change_eltype(::Type{Complex{T}}, ::Val{32}) where {T<:Union{Int,AbstractFloat}} = ComplexF32
-
 QuantumToolbox.to_dense(A::MT) where {MT<:AbstractCuSparseArray} = CuArray(A)
 
 QuantumToolbox.to_dense(::Type{T1}, A::CuArray{T2}) where {T1<:Number,T2<:Number} = CuArray{T1}(A)
diff --git a/src/utilities.jl b/src/utilities.jl
index 0a660995f..a3547cf61 100644
--- a/src/utilities.jl
+++ b/src/utilities.jl
@@ -190,3 +190,10 @@ _CType(::Type{Complex{Int32}}) = ComplexF32
 _CType(::Type{Complex{Int64}}) = ComplexF64
 _CType(::Type{Complex{Float32}}) = ComplexF32
 _CType(::Type{Complex{Float64}}) = ComplexF64
+
+_convert_eltype_wordsize(::Type{T}, ::Val{64}) where {T<:Int} = Int64
+_convert_eltype_wordsize(::Type{T}, ::Val{32}) where {T<:Int} = Int32
+_convert_eltype_wordsize(::Type{T}, ::Val{64}) where {T<:AbstractFloat} = Float64
+_convert_eltype_wordsize(::Type{T}, ::Val{32}) where {T<:AbstractFloat} = Float32
+_convert_eltype_wordsize(::Type{Complex{T}}, ::Val{64}) where {T<:Union{Int,AbstractFloat}} = ComplexF64
+_convert_eltype_wordsize(::Type{Complex{T}}, ::Val{32}) where {T<:Union{Int,AbstractFloat}} = ComplexF32