--- a/src/eric7/UI/Previewers/PreviewerHTML.py	Sun Dec 03 16:44:52 2023 +0100
+++ b/src/eric7/UI/Previewers/PreviewerHTML.py	Sun Dec 03 19:46:34 2023 +0100
@@ -700,7 +700,7 @@
         if "sphinx" in sys.modules:
             # Make sure any Sphinx polution of docutils has been removed.
             unloadKeys = [
-                k for k in sys.modules.keys() if k.startswith(("docutils", "sphinx"))
+                k for k in sys.modules if k.startswith(("docutils", "sphinx"))
             ]
             for key in unloadKeys:
                 sys.modules.pop(key)