diff --git a/smbus2/smbus2.pyi b/smbus2/smbus2.pyi
index 5930268..2315e12 100644
--- a/smbus2/smbus2.pyi
+++ b/smbus2/smbus2.pyi
@@ -69,7 +69,7 @@ class i2c_smbus_ioctl_data(Structure):
 class i2c_msg(Structure):
     def __iter__(self) -> Iterator[int]: ...
     def __len__(self) -> int: ...
-    def __bytes__(self) -> str: ...
+    def __bytes__(self) -> bytes: ...
     @staticmethod
     def read(address: int, length: int) -> "i2c_msg": ...
     @staticmethod