diff --git a/argcomplete/packages/_argparse.py b/argcomplete/packages/_argparse.py
index 2a064f9..d10cf01 100644
--- a/argcomplete/packages/_argparse.py
+++ b/argcomplete/packages/_argparse.py
@@ -162,6 +162,8 @@ def take_action(action, argument_strings, option_string=None):
         def consume_optional(start_index):
             # get the optional identified at this index
             option_tuple = option_string_indices[start_index]
+            if isinstance(option_tuple, list):  # Python 3.12.7+
+                option_tuple = option_tuple[0]
             if len(option_tuple) == 3:
                 action, option_string, explicit_arg = option_tuple
             else:  # Python 3.11.9+, 3.12.3+, 3.13+