diff --git a/pyproject.toml b/pyproject.toml
index baa56392..14755dfc 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -22,16 +22,13 @@ keywords = [
     "physics",
 ]
 readme = "README.rst"
-requires-python = ">=3.9"
+requires-python = "3.9"
 classifiers = [
     "Intended Audience :: Science/Research",
     "Development Status :: 5 - Production/Stable",
     "License :: OSI Approved :: MIT License",
     "Natural Language :: English",
     "Programming Language :: Python :: 3.9",
-    "Programming Language :: Python :: 3.10",
-    "Programming Language :: Python :: 3.11",
-    "Programming Language :: Python :: 3.12",
     "Programming Language :: Cython",
     "Programming Language :: C++",
     "Operating System :: POSIX :: Linux",
diff --git a/test/test_space.py b/test/test_space.py
index 755869a2..f2bff072 100644
--- a/test/test_space.py
+++ b/test/test_space.py
@@ -964,6 +964,7 @@ def test_python_cython_osm_graph():
     cy_graph = CyGraph.from_nx(g_proj, make_attribute_distance="length")
     py_graph = Graph.from_nx(g_proj, make_attribute_distance="length")
 
+    # mnemonic: d = distance, cy = cython, py = python, h = high node, o = other node
     dcyho = cy_graph.d(high_node_id, other_node_id)
     dpyho = py_graph.d(high_node_id, other_node_id)
     dcyoh = cy_graph.d(other_node_id, high_node_id)