diff --git a/stubs/cffi/_cffi_backend.pyi b/stubs/cffi/_cffi_backend.pyi
index 1b3d8f20e441..5724b092da7c 100644
--- a/stubs/cffi/_cffi_backend.pyi
+++ b/stubs/cffi/_cffi_backend.pyi
@@ -203,7 +203,7 @@ class FFI:
     def offsetof(self, __cdecl: str | CType, __field_or_index: str | int, *__fields_or_indexes: str | int) -> int: ...
     def release(self, __cdata: CData) -> None: ...
     def sizeof(self, __cdecl: str | CType | CData) -> int: ...
-    def string(self, cdata: CData, maxlen: int) -> bytes | str: ...
+    def string(self, cdata: CData, maxlen: int = -1) -> bytes | str: ...
     def typeof(self, cdecl: str | CData) -> CType: ...
     def unpack(self, cdata: CData, length: int) -> bytes | str | list[Any]: ...