diff --git a/fastapi_code_generator/parser.py b/fastapi_code_generator/parser.py
index 579f601..ed05a3d 100644
--- a/fastapi_code_generator/parser.py
+++ b/fastapi_code_generator/parser.py
@@ -184,7 +184,7 @@ def __init__(
         encoding: str = 'utf-8',
         enum_field_as_literal: Optional[LiteralType] = None,
         set_default_enum_member: bool = False,
-        strict_nullable: bool = False,
+        strict_nullable: bool = True,
         use_generic_container_types: bool = False,
         enable_faux_immutability: bool = False,
         remote_text_cache: Optional[DefaultPutDict[str, str]] = None,