diff --git a/stdlib/imaplib.pyi b/stdlib/imaplib.pyi
index eef1c1957..b08210077 100644
--- a/stdlib/imaplib.pyi
+++ b/stdlib/imaplib.pyi
@@ -169,7 +169,7 @@ class _Authenticator:
     def encode(self, inp: bytes) -> str: ...
     def decode(self, inp: str) -> bytes: ...
 
-def Internaldate2tuple(resp: str) -> time.struct_time: ...
+def Internaldate2tuple(resp: bytes) -> time.struct_time: ...
 def Int2AP(num: int) -> str: ...
 def ParseFlags(resp: str) -> tuple[str, ...]: ...
 def Time2Internaldate(date_time: float | time.struct_time | str) -> str: ...