diff --git a/Project.toml b/Project.toml
index 8fc4a3d6b..499039037 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "MPSKit"
 uuid = "bb1c41ca-d63c-52ed-829e-0820dda26502"
-version = "0.13.11"
+version = "0.13.12"
 authors = "Lukas Devos, Maarten Van Damme and contributors"
 
 [deps]
diff --git a/src/algorithms/derivatives/hamiltonian_derivatives.jl b/src/algorithms/derivatives/hamiltonian_derivatives.jl
index d1c64f38c..0221ae484 100644
--- a/src/algorithms/derivatives/hamiltonian_derivatives.jl
+++ b/src/algorithms/derivatives/hamiltonian_derivatives.jl
@@ -301,7 +301,7 @@ function prepare_operator!!(
         missing
     elseif !ismissing(AB) && !ismissing(H.CB)
         Id = TensorKit.id(storagetype(H.CB), space(AB, 3))
-        @plansor CA[-1 -2 -3; -4 -5 -6] += H.CB[-2 -3; -5 -6] * Id[-1; -4]
+        @plansor AB[-1 -2 -3; -4 -5 -6] += H.CB[-2 -3; -5 -6] * Id[-1; -4]
         missing
     else
         H.CB