diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index 7b0b5c3..1a7cdde 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -33,10 +33,10 @@ jobs:
           # build (pure-Rust zlib-rs) does not need it.
           apt-get install -y --no-install-recommends python3 python3-venv cmake
           python3 -m venv /opt/interop
-          /opt/interop/bin/pip install --no-cache-dir h5py numpy netCDF4 xarray
+          /opt/interop/bin/pip install --no-cache-dir h5py numpy netCDF4 xarray hdf5plugin
           echo "/opt/interop/bin" >> "$GITHUB_PATH"
       - name: Show interop library versions
-        run: /opt/interop/bin/python -c "import h5py, netCDF4; print('h5py', h5py.__version__, 'HDF5', h5py.version.hdf5_version, 'netCDF4', netCDF4.__version__)"
+        run: /opt/interop/bin/python -c "import h5py, netCDF4, hdf5plugin; print('h5py', h5py.__version__, 'HDF5', h5py.version.hdf5_version, 'netCDF4', netCDF4.__version__, 'hdf5plugin', hdf5plugin.version)"
       - name: Run CI script
         env:
           # Name the interpreter outright rather than relying on $GITHUB_PATH
diff --git a/scripts/ci-test.sh b/scripts/ci-test.sh
index b52c88b..1d7a7f9 100755
--- a/scripts/ci-test.sh
+++ b/scripts/ci-test.sh
@@ -145,8 +145,10 @@ run_step "cargo test (fast-deflate / zlib-ng)" cargo test \
 #    skipping — the tests read the same variable.
 PYTHON="${CLAWHDF5_PYTHON:-python3}"
 if "$PYTHON" -c "import h5py" >/dev/null 2>&1 || [ "${CLAWHDF5_REQUIRE_INTEROP:-0}" = "1" ]; then
+    # lz4/zstd so the hdf5plugin round-trips (our LZ4 and Zstd output read by
+    # libhdf5's registered plugins) compile and run too.
     run_step "h5py interop (format, ignored tests)" cargo test \
-        -p clawhdf5-format --test writer_h5py_tests -- --include-ignored
+        -p clawhdf5-format --features lz4,zstd --test writer_h5py_tests -- --include-ignored
 else
     echo ""
     echo "==> [h5py interop] SKIPPED: no h5py in $PYTHON"