diff --git a/GeoHealthCheck/plugins/probe/wmsdrilldown.py b/GeoHealthCheck/plugins/probe/wmsdrilldown.py
index 24adf69a..2b73f02d 100644
--- a/GeoHealthCheck/plugins/probe/wmsdrilldown.py
+++ b/GeoHealthCheck/plugins/probe/wmsdrilldown.py
@@ -63,7 +63,7 @@ def perform_request(self):
         result.start()
         try:
             # Pick a random layer
-            layer_name = random.sample(wms.contents.keys(), 1)[0]
+            layer_name = random.sample(list(wms.contents.keys()), 1)[0]
             layer = wms[layer_name]
 
             # TODO Only use EPSG:4326, later random CRS
diff --git a/docs/install.rst b/docs/install.rst
index e934f000..3efa37df 100644
--- a/docs/install.rst
+++ b/docs/install.rst
@@ -32,7 +32,8 @@ for installation and management. ``Cron`` was used for scheduling the actual
 healthchecks before v0.5.0.
 
 Starting from version v0.8.0.0 GeoHealthCheck requires **python 3**. Previous
-versions require **python 2**.
+versions require **python 2**. GeoHealthCheck is at least compatible with Python versions
+up to and including `3.12.3`. Higher Python versions may work but are untested.
 
 Install
 -------