diff --git a/demo/horizontal/emmo2meta.py b/demo/horizontal/emmo2meta.py
index 1c4538938..91753a914 100644
--- a/demo/horizontal/emmo2meta.py
+++ b/demo/horizontal/emmo2meta.py
@@ -393,7 +393,7 @@ def get_description(self, cls):
         """Returns description for OWL class `cls` by combining its
         annotations."""
         if isinstance(cls, str):
-            cls = onto[cls]
+            cls = self.onto[cls]
         descr = []
         annotations = self.onto.get_annotations(cls)
         if "definition" in annotations:
diff --git a/requirements_dev.txt b/requirements_dev.txt
index 8014a9c35..188c04c0b 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -1,5 +1,6 @@
 pre-commit>=2.21.0,<3; python_version<"3.8"
 pre-commit~=3.4; python_version>="3.8"
-pylint~=3.0
+pylint~=2.17; python_version<"3.8"
+pylint~=3.0; python_version>="3.8"
 pytest~=7.4
 pytest-cov~=4.1