diff --git a/stdlib/3/email/generator.pyi b/stdlib/3/email/generator.pyi
index 81e733b7a..2cf3942d3 100644
--- a/stdlib/3/email/generator.pyi
+++ b/stdlib/3/email/generator.pyi
@@ -1,6 +1,6 @@
 # Stubs for email.generator (Python 3.4)
 
-from typing import TextIO, Optional
+from typing import BinaryIO, TextIO, Optional
 from email.message import Message
 from email.policy import Policy
 
@@ -14,9 +14,9 @@ class Generator:
                 linesep: Optional[str] = ...) -> None: ...
 
 class BytesGenerator:
-    def clone(self, fp: TextIO) -> Generator: ...
+    def clone(self, fp: BinaryIO) -> BytesGenerator: ...
     def write(self, s: str) -> None: ...
-    def __init__(self, outfp: TextIO, mangle_from_: bool = ...,
+    def __init__(self, outfp: BinaryIO, mangle_from_: bool = ...,
                  maxheaderlen: int = ..., *,
                  policy: Policy = ...) -> None: ...
     def flatten(self, msg: Message, unixfrom: bool = ...,