diff --git a/pyproject.toml b/pyproject.toml
index 816f0c87f..0129eca1d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,12 +15,15 @@ classifiers = [
 documentation = "https://docs.dasch.swiss/latest/DSP-TOOLS/"
 homepage = "https://www.dasch.swiss/"
 repository = "https://github.com/dasch-swiss/dsp-tools"
-include = ["src/dsp_tools/resources/*"]
+include = [
+    "src/dsp_tools/resources/*",
+    "src/dsp_tools/py.typed"  # see https://mypy.readthedocs.io/en/stable/installed_packages.html#making-pep-561-compatible-packages
+]
 exclude = ["src/dsp_tools/import_scripts/*"]
 
 
 [tool.poetry.dependencies]
-python = ">=3.9,<3.12"
+python = "^3.9"
 jsonpath-ng = "^1.5.3"
 argparse = "^1.4.0"
 lxml = "^4.9.2"
diff --git a/src/dsp_tools/py.typed b/src/dsp_tools/py.typed
new file mode 100644
index 000000000..e69de29bb