diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 337d3ef4..1b9324be 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,6 +1,5 @@
 {
     "tket2-py": "0.6.0",
-    "tket2-eccs": "0.3.0",
     "tket2-eccs": "0.2.0",
-    "tket2-exts": "0.3.0"
+    "tket2-exts": "0.4.0"
 }
\ No newline at end of file
diff --git a/tket2-exts/CHANGELOG.md b/tket2-exts/CHANGELOG.md
index a062623c..dfa30adb 100644
--- a/tket2-exts/CHANGELOG.md
+++ b/tket2-exts/CHANGELOG.md
@@ -1,5 +1,42 @@
 # Changelog
 
+## [0.4.0](https://github.com/CQCL/tket2/compare/tket2-exts-v0.3.0...tket2-exts-v0.4.0) (2025-01-16)
+
+
+### ⚠ BREAKING CHANGES
+
+* **tket2-hseries:** The signature of `QSystemOp::LazyMeasure` is changed to consume its qubit.
+* Updated `hugr` rust dependency to `0.14.0` Extension are now defined in `hugr 0.14` style. Replaced the `ROTATION_TYPE` with a method call, and dropped the per-extension registry definitions.
+* all references to "hseries" including extension, modules and structs renamed to "qsystem"
+* hseries qalloc op replaced with fallible TryQalloc
+
+### Features
+
+* move extensions to auxillary package ([#682](https://github.com/CQCL/tket2/issues/682)) ([dd78f9a](https://github.com/CQCL/tket2/commit/dd78f9a571905407bcf74131a54f4aefbca740c4))
+* **tket2-hseries:** Add `tket2.wasm` extension ([#737](https://github.com/CQCL/tket2/issues/737)) ([34bdc21](https://github.com/CQCL/tket2/commit/34bdc218b5e9bf334830873e847935dea0053242))
+* **tket2-hseries:** Redefine `QSystemOp::LazyMeasure` and introduce `QSystemOp::LazyMeasureReset` ([#741](https://github.com/CQCL/tket2/issues/741)) ([1f126c0](https://github.com/CQCL/tket2/commit/1f126c0a4f7686fa6941a05aa28228786baac6d1))
+* update measurement and alloc operations ([#702](https://github.com/CQCL/tket2/issues/702)) ([a7a0201](https://github.com/CQCL/tket2/commit/a7a020116f42bfeb89c356d08816a2f3ce1b5226))
+
+
+### Bug Fixes
+
+* remove unicode pi symbols in rotation extension ([#743](https://github.com/CQCL/tket2/issues/743)) ([b3ed351](https://github.com/CQCL/tket2/commit/b3ed35108d5fe93c3aa8101084b695470c488a30))
+
+
+### Documentation
+
+* docstring capitalisation ([#686](https://github.com/CQCL/tket2/issues/686)) ([e18f921](https://github.com/CQCL/tket2/commit/e18f921903953dc6a033ef697092f80a99a142b0))
+
+
+### Miscellaneous Chores
+
+* Update to next version of hugr ([#720](https://github.com/CQCL/tket2/issues/720)) ([4a3a5a5](https://github.com/CQCL/tket2/commit/4a3a5a5e38252d4ee709e7e97bb5a1e90bd9fff4))
+
+
+### Code Refactoring
+
+* rename hseries to qsystem ([#703](https://github.com/CQCL/tket2/issues/703)) ([1e90173](https://github.com/CQCL/tket2/commit/1e90173872e73c44a6321fe400ae6f2e4e115220))
+
 ## [0.3.0](https://github.com/CQCL/tket2/compare/tket2-exts-v0.2.0...tket2-exts-v0.3.0) (2024-12-16)
 
 
diff --git a/tket2-exts/pyproject.toml b/tket2-exts/pyproject.toml
index 5b7f7c72..d8d32648 100644
--- a/tket2-exts/pyproject.toml
+++ b/tket2-exts/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "tket2-exts"
-version = "0.3.0"
+version = "0.4.0"
 requires-python = ">=3.10"
 description = "HUGR extension definitions for the tket2 compiler."
 license = { file = "LICENCE" }
diff --git a/tket2-exts/src/tket2_exts/__init__.py b/tket2-exts/src/tket2_exts/__init__.py
index 448c6a3a..29ae7eb7 100644
--- a/tket2-exts/src/tket2_exts/__init__.py
+++ b/tket2-exts/src/tket2_exts/__init__.py
@@ -8,7 +8,7 @@
 
 # This is updated by our release-please workflow, triggered by this
 # annotation: x-release-please-version
-__version__ = "0.3.0"
+__version__ = "0.4.0"
 
 
 @functools.cache