diff --git a/Project.toml b/Project.toml
index 77aefefbf..a0cf0b881 100644
--- a/Project.toml
+++ b/Project.toml
@@ -51,7 +51,7 @@ Graphs = "1.7"
 IncompleteLU = "0.2"
 KernelAbstractions = "0.9.2"
 LinearAlgebra = "1"
-LinearSolve = "2"
+LinearSolve = "2, 3"
 OrdinaryDiffEqCore = "1"
 OrdinaryDiffEqTsit5 = "1"
 Pkg = "1"
diff --git a/src/qobj/arithmetic_and_attributes.jl b/src/qobj/arithmetic_and_attributes.jl
index 15a0f430d..e4aa070f8 100644
--- a/src/qobj/arithmetic_and_attributes.jl
+++ b/src/qobj/arithmetic_and_attributes.jl
@@ -443,7 +443,7 @@ LinearAlgebra.exp(
 ) where {ObjType<:Union{OperatorQuantumObject,SuperOperatorQuantumObject},DimsType} =
     QuantumObject(_spexp(A.data), A.type, A.dimensions)
 
-function _spexp(A::SparseMatrixCSC{T,M}; threshold = 1e-14, nonzero_tol = 1e-20) where {T,M}
+function _spexp(A::SparseMatrixCSC{T,M}; threshold = 1e-14, nonzero_tol = 1e-20) where {T<:Number,M<:Int}
     m = checksquare(A) # Throws exception if not square
 
     mat_norm = norm(A, Inf)