diff --git a/stdlib/2/binascii.pyi b/stdlib/2/binascii.pyi
deleted file mode 100644
index f8b85b6da478..000000000000
--- a/stdlib/2/binascii.pyi
+++ /dev/null
@@ -1,21 +0,0 @@
-"""Stubs for the binascii module."""
-
-def a2b_base64(string: str) -> str: ...
-def a2b_hex(hexstr: str) -> str: ...
-def a2b_hqx(string: str) -> str: ...
-def a2b_qp(string: str, header: bool = ...) -> str: ...
-def a2b_uu(string: str) -> str: ...
-def b2a_base64(data: str) -> str: ...
-def b2a_hex(data: str) -> str: ...
-def b2a_hqx(data: str) -> str: ...
-def b2a_qp(data: str, quotetabs: bool = ..., istext: bool = ..., header: bool = ...) -> str: ...
-def b2a_uu(data: str) -> str: ...
-def crc32(data: str, crc: int = None) -> int: ...
-def crc_hqx(data: str, oldcrc: int) -> int: ...
-def hexlify(data: str) -> str: ...
-def rlecode_hqx(data: str) -> str: ...
-def rledecode_hqx(data: str) -> str: ...
-def unhexlify(hexstr: str) -> str: ...
-
-class Error(Exception): ...
-class Incomplete(Exception): ...
diff --git a/stdlib/2and3/binascii.pyi b/stdlib/2and3/binascii.pyi
new file mode 100644
index 000000000000..393c4afcb8ce
--- /dev/null
+++ b/stdlib/2and3/binascii.pyi
@@ -0,0 +1,45 @@
+# Stubs for binascii
+
+# Based on http://docs.python.org/3.2/library/binascii.html
+
+import sys
+from typing import Union, Text
+
+
+if sys.version_info < (3,):
+    # Python 2 accepts unicode ascii pretty much everywhere.
+    _Bytes = Union[bytes, Text]
+    _Ascii = Union[bytes, Text]
+elif sys.version_info < (3, 3):
+    # Python 3.2 and below only accepts bytes.
+    _Bytes = bytes
+    _Ascii = bytes
+else:
+    # But since Python 3.3 ASCII-only unicode strings are accepted by the
+    # a2b_* functions.
+    _Bytes = bytes
+    _Ascii = Union[bytes, Text]
+
+def a2b_uu(string: _Ascii) -> bytes: ...
+def b2a_uu(data: _Bytes) -> bytes: ...
+def a2b_base64(string: _Ascii) -> bytes: ...
+if sys.version_info >= (3, 6):
+    def b2a_base64(data: _Bytes, *, newline: bool = ...) -> bytes: ...
+else:
+    def b2a_base64(data: _Bytes) -> bytes: ...
+def a2b_qp(string: _Ascii, header: bool = ...) -> bytes: ...
+def b2a_qp(data: _Bytes, quotetabs: bool = ..., istext: bool = ...,
+             header: bool = ...) -> bytes: ...
+def a2b_hqx(string: _Ascii) -> bytes: ...
+def rledecode_hqx(data: _Bytes) -> bytes: ...
+def rlecode_hqx(data: _Bytes) -> bytes: ...
+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: ...
+def a2b_hex(hexstr: _Ascii) -> bytes: ...
+def unhexlify(hexlify: _Ascii) -> bytes: ...
+
+class Error(Exception): ...
+class Incomplete(Exception): ...
diff --git a/stdlib/3/binascii.pyi b/stdlib/3/binascii.pyi
deleted file mode 100644
index edbd97012b18..000000000000
--- a/stdlib/3/binascii.pyi
+++ /dev/null
@@ -1,26 +0,0 @@
-# Stubs for binascii
-
-# Based on http://docs.python.org/3.2/library/binascii.html
-
-from typing import Union
-
-def a2b_uu(string: Union[str, bytes]) -> bytes: ...
-def b2a_uu(data: bytes) -> bytes: ...
-def a2b_base64(string: Union[str, bytes]) -> bytes: ...
-def b2a_base64(data: bytes) -> bytes: ...
-def a2b_qp(string: Union[str, bytes], header: bool = ...) -> bytes: ...
-def b2a_qp(data: bytes, quotetabs: bool = ..., istext: bool = ...,
-             header: bool = ...) -> bytes: ...
-def a2b_hqx(string: Union[str, bytes]) -> bytes: ...
-def rledecode_hqx(data: bytes) -> bytes: ...
-def rlecode_hqx(data: bytes) -> bytes: ...
-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: ...
-def a2b_hex(hexstr: Union[str, bytes]) -> bytes: ...
-def unhexlify(hexlify: Union[str, bytes]) -> bytes: ...
-
-class Error(Exception): ...
-class Incomplete(Exception): ...