diff --git a/stdlib/2and3/binascii.pyi b/stdlib/2and3/binascii.pyi
index d268a1b6a..542e1a249 100644
--- a/stdlib/2and3/binascii.pyi
+++ b/stdlib/2and3/binascii.pyi
@@ -34,7 +34,10 @@ def b2a_hqx(data: _Bytes) -> bytes: ...
 def crc_hqx(data: _Bytes, crc: int) -> int: ...
 def crc32(data: _Bytes, crc: int = ...) -> int: ...
 def b2a_hex(data: _Bytes) -> bytes: ...
-def hexlify(data: _Bytes) -> bytes: ...
+if sys.version_info >= (3, 8):
+    def hexlify(data: bytes, sep: Union[str, bytes] = ..., bytes_per_sep: int = ...) -> bytes: ...
+else:
+    def hexlify(data: _Bytes) -> bytes: ...
 def a2b_hex(hexstr: _Ascii) -> bytes: ...
 def unhexlify(hexlify: _Ascii) -> bytes: ...