diff --git a/CHANGELOG.md b/CHANGELOG.md
index d53e8db88..3ddde011d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,7 @@
 
 # News
 
-## v0.9.4 - 2024-06-19
+## v0.9.4 - 2024-06-28
 
 - Addition of a constructor for concatenated quantum codes -- `Concat`.
 - Addition of multiple unexported classical code constructors.
@@ -13,6 +13,7 @@
 - Gate errors are now conveniently supported by the various ECC benchmark setups in the `ECC` module.
 - Remove printing of spurious debug info from the PyBP decoder. 
 - Significant improvements to the low-level circuit compiler (the sumtype compactifier), leading to faster Pauli frame simulation of noisy circuits.
+- Bump `QuantumOpticsBase.jl` package extension compat bound.
 
 ## v0.9.3 - 2024-04-10
 
diff --git a/Project.toml b/Project.toml
index efbf60078..7e351585a 100644
--- a/Project.toml
+++ b/Project.toml
@@ -59,7 +59,7 @@ PrecompileTools = "1.2"
 PyQDecoders = "0.2.1"
 Quantikz = "1.3.1"
 QuantumInterface = "0.3.3"
-QuantumOpticsBase = "0.4.18"
+QuantumOpticsBase = "0.4.18, 0.5"
 Random = "1.9"
 SIMD = "3.4.0"
 SparseArrays = "1.9"