diff --git a/Project.toml b/Project.toml
index c1db7ab..f832214 100644
--- a/Project.toml
+++ b/Project.toml
@@ -13,7 +13,7 @@ Roots = "f2b01f46-fcfa-551c-844a-d8ac1e96c665"
 
 [compat]
 Arpack = "0.3, 0.4, 0.5"
-BlockBandedMatrices = "0.7, 0.8, 0.9, 0.10, 0.11, 0.12"
+BlockBandedMatrices = "0.12, 0.13"
 Distributions = "0.22, 0.23, 0.24, 0.25"
 FillArrays = "0.8, 0.9, 0.10, 0.11, 0.12, 0.13, 1"
 KrylovKit = "0.4, 0.5, 0.6"
diff --git a/src/InfinitesimalGenerators.jl b/src/InfinitesimalGenerators.jl
index d73e527..6f1572b 100644
--- a/src/InfinitesimalGenerators.jl
+++ b/src/InfinitesimalGenerators.jl
@@ -12,7 +12,6 @@ using BlockBandedMatrices: BandedBlockBandedMatrix, Block
 
 
 
-
 include("MarkovProcess.jl")
 include("AdditiveFunctional.jl")
 include("feynman_kac.jl")
diff --git a/src/jointoperator.jl b/src/jointoperator.jl
index 59e6593..d89383c 100644
--- a/src/jointoperator.jl
+++ b/src/jointoperator.jl
@@ -8,13 +8,10 @@ function jointoperator(operators, Q::Array)
     # same as the number of operators 
     @assert size(Q,1) == size(Q,2) == N
     J = BandedBlockBandedMatrix(Zeros(wn * N, wn * N), fill(wn, N) ,fill(wn, N), (N-1, N-1), (1, 1))
-    for i in 1:N
-        J[Block(i,i)] = operators[i]
-    end
     for i in 1:N
         for j in 1:N
-            J[Block(i,j)] += Tridiagonal(zeros(wn -1), fill(Q[i, j], wn), zeros(wn-1))
+            J[Block(i,j)] = Q[i, j] * I(wn) + (i == j) * operators[i]
         end
     end
     return J
-end
\ No newline at end of file
+end