diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0086a7b..3cccf8e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # News
 
+## v0.4.3 - 2024-08-13
+
+- **(fix)** Fix for incorrect basis for `express(_,::QuantumOpticsRepr)` for certain operators.
+
 ## v0.4.2 - 2024-08-11
 
 - `@withmetadata` now supports inline docstrings for struct fields
diff --git a/Project.toml b/Project.toml
index b5021c0..76f73a4 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "QuantumSymbolics"
 uuid = "efa7fd63-0460-4890-beb7-be1bbdfbaeae"
 authors = ["QuantumSymbolics.jl contributors"]
-version = "0.4.2"
+version = "0.4.3"
 
 [deps]
 Latexify = "23fbe1c1-3f47-55db-b15f-69d7ec21a316"
diff --git a/ext/QuantumOpticsExt/QuantumOpticsExt.jl b/ext/QuantumOpticsExt/QuantumOpticsExt.jl
index 311e171..81ca2fa 100644
--- a/ext/QuantumOpticsExt/QuantumOpticsExt.jl
+++ b/ext/QuantumOpticsExt/QuantumOpticsExt.jl
@@ -71,14 +71,25 @@ express_nolookup(s::XBasisState, ::QuantumOpticsRepr) = (_s₊,_s₋)[s.idx]
 express_nolookup(s::YBasisState, ::QuantumOpticsRepr) = (_i₊,_i₋)[s.idx]
 express_nolookup(s::ZBasisState, ::QuantumOpticsRepr) = (_l0,_l1)[s.idx]
 
-express_nolookup(s::FockState, r::QuantumOpticsRepr) = fockstate(FockBasis(r.cutoff),s.idx)
-express_nolookup(s::CoherentState, r::QuantumOpticsRepr) = coherentstate(FockBasis(r.cutoff),s.alpha)
-express_nolookup(o::NumberOp, r::QuantumOpticsRepr) = number(FockBasis(r.cutoff))
-express_nolookup(o::CreateOp, r::QuantumOpticsRepr) = create(FockBasis(r.cutoff))
-express_nolookup(o::DestroyOp, r::QuantumOpticsRepr) = destroy(FockBasis(r.cutoff))
-express_nolookup(o::DisplaceOp, r::QuantumOpticsRepr) = displace(FockBasis(r.cutoff), o.alpha)
-express_nolookup(x::MixedState, ::QuantumOpticsRepr) = identityoperator(basis(x))/length(basis(x)) # TODO there is probably a more efficient way to represent it
-express_nolookup(x::IdentityOp, r::QuantumOpticsRepr) = identityoperator(FockBasis(r.cutoff))
+function finite_basis(s,r)
+    if isfinite(length(basis(s)))
+        return basis(s)
+    else
+        if isa(basis(s), FockBasis)
+            return FockBasis(r.cutoff)
+        else
+            error()
+        end
+    end
+end
+express_nolookup(s::FockState, r::QuantumOpticsRepr) = fockstate(finite_basis(s,r),s.idx)
+express_nolookup(s::CoherentState, r::QuantumOpticsRepr) = coherentstate(finite_basis(s,r),s.alpha)
+express_nolookup(o::NumberOp, r::QuantumOpticsRepr) = number(finite_basis(o,r))
+express_nolookup(o::CreateOp, r::QuantumOpticsRepr) = create(finite_basis(o,r))
+express_nolookup(o::DestroyOp, r::QuantumOpticsRepr) = destroy(finite_basis(o,r))
+express_nolookup(o::DisplaceOp, r::QuantumOpticsRepr) = displace(finite_basis(o,r), o.alpha)
+express_nolookup(x::MixedState, r::QuantumOpticsRepr) = identityoperator(finite_basis(x,r))/length(finite_basis(x,r)) # TODO there is probably a more efficient way to represent it
+express_nolookup(x::IdentityOp, r::QuantumOpticsRepr) = identityoperator(finite_basis(x,r))
 
 express_nolookup(p::PauliNoiseCPTP, ::QuantumOpticsRepr) = LazySuperSum(SpinBasis(1//2), [1-p.px-p.py-p.pz,p.px,p.py,p.pz],
                                                                [LazyPrePost(_id,_id),LazyPrePost(_x,_x),LazyPrePost(_y,_y),LazyPrePost(_z,_z)])