diff --git a/.github/change-filters.yml b/.github/change-filters.yml
index aaa916bc2..f0ecf5db7 100644
--- a/.github/change-filters.yml
+++ b/.github/change-filters.yml
@@ -1,7 +1,7 @@
 # Filters used by [dorny/path-filters](https://github.com/dorny/paths-filter)
 # to detect changes in each subproject, and only run the corresponding jobs.
 
-rust:
+rust: &rust
   - "hugr/**"
   - "hugr-cli/**"
   - "hugr-core/**"
@@ -11,6 +11,7 @@ rust:
   - ".github/workflows/ci-rs.yml"
 
 python:
+  - *rust
   - "hugr-py/**"
   - "pyproject.toml"
   - "poetry.lock"
diff --git a/hugr-py/tests/conftest.py b/hugr-py/tests/conftest.py
index a3d70a399..6da88c4ba 100644
--- a/hugr-py/tests/conftest.py
+++ b/hugr-py/tests/conftest.py
@@ -121,7 +121,7 @@ def validate(h: Hugr, mermaid: bool = False, roundtrip: bool = True):
     workspace_dir = pathlib.Path(__file__).parent.parent.parent
     # use the HUGR_BIN environment variable if set, otherwise use the debug build
     bin_loc = os.environ.get("HUGR_BIN", str(workspace_dir / "target/debug/hugr"))
-    cmd = [bin_loc, "-"]
+    cmd = [bin_loc, "validate", "-"]
 
     if mermaid:
         cmd.append("--mermaid")