diff --git a/tiramisu_cmdline_parser/api.py b/tiramisu_cmdline_parser/api.py
index 17cf642..85dfdde 100644
--- a/tiramisu_cmdline_parser/api.py
+++ b/tiramisu_cmdline_parser/api.py
@@ -122,7 +122,7 @@ class TiramisuNamespace(Namespace):
                 else:
                     display_value = true_value
                 choices = get_choice_list(option, option.property.get(), False)
-                raise ValueError("argument {}: invalid choice: '{}' (choose from {})".format(self.arguments[key], display_value, ', '.join([f"'{val}'" for val in choices])))
+                raise ValueError("argument {}: invalid choice: '{}' (choose from {})".format(self.arguments[key], display_value, ', '.join(["'{}'".format(val) for val in choices])))
             else:
                 raise err