diff --git a/modules/core.py b/modules/core.py
index 20f25c7..b59e639 100644
--- a/modules/core.py
+++ b/modules/core.py
@@ -51,12 +51,23 @@ class _DuplicateAwareConfigParser(configparser.ConfigParser):
         super().__init__(*args, **kwargs)
 
     def _handle_option(self, st, line, fpname):
-        if st.optname in st.options:
-            logging.getLogger(__name__).error(
-                "Duplicate option in config file: section [%s], option '%s' (file %s, line %s). Using last value.",
-                st.sectname, st.optname, fpname, getattr(st, 'lineno', '?'),
-            )
-        st.options[st.optname] = st.optvalue
+        # Python 3.13+ uses st.cursect; older internals used st.options (both mean current section dict).
+        sect = getattr(st, 'cursect', None) or getattr(st, 'options', None)
+        if sect is not None:
+            # Duplicate check: in 3.13 optname is set inside base _handle_option, so parse line here for the check.
+            line_str = getattr(line, 'clean', None)
+            if line_str is None:
+                line_str = line if isinstance(line, str) else str(line)
+            mo = self._optcre.match(line_str) if line_str else None
+            if mo:
+                optname = self.optionxform(mo.group('option').rstrip())
+                if optname in sect:
+                    logging.getLogger(__name__).error(
+                        "Duplicate option in config file: section [%s], option '%s' (file %s, line %s). Using last value.",
+                        getattr(st, 'sectname', '?'), optname, fpname, getattr(st, 'lineno', '?'),
+                    )
+        # Delegate to base to parse line and set option (required on Python 3.13+).
+        super()._handle_option(st, line, fpname)
 
 
 class MeshCoreBot: