diff --git a/discord/ext/commands/hybrid.py b/discord/ext/commands/hybrid.py
index 99b537ca1..c584aca8f 100644
--- a/discord/ext/commands/hybrid.py
+++ b/discord/ext/commands/hybrid.py
@@ -256,7 +256,7 @@ def replace_parameter(
                 # Special case Optional[X] where X is a single type that can optionally be a converter
                 inner = args[0]
                 is_inner_transformer = is_transformer(inner)
-                if is_converter(inner) and not is_inner_transformer:
+                if (is_converter(inner) or inner in CONVERTER_MAPPING) and not is_inner_transformer:
                     param = param.replace(annotation=Optional[ConverterTransformer(inner, original)])
             else:
                 raise