diff --git a/shared-bindings/usb_midi/PortIn.c b/shared-bindings/usb_midi/PortIn.c
index 9d9310b47a..176283cd50 100644
--- a/shared-bindings/usb_midi/PortIn.c
+++ b/shared-bindings/usb_midi/PortIn.c
@@ -48,7 +48,7 @@
 
 // These are standard stream methods. Code is in py/stream.c.
 //
-//|     def read(self, nbytes: Any = None) -> Any:
+//|     def read(self, nbytes: int = None) -> Optional[bytes]:
 //|         """Read characters.  If ``nbytes`` is specified then read at most that many
 //|         bytes. Otherwise, read everything that arrives until the connection
 //|         times out. Providing the number of bytes expected is highly recommended
@@ -58,7 +58,7 @@
 //|         :rtype: bytes or None"""
 //|         ...
 //|
-//|     def readinto(self, buf: Any, nbytes: Any = None) -> Any:
+//|     def readinto(self, buf: WriteableBuffer, nbytes: int = None) -> Optional[bytes]:
 //|         """Read bytes into the ``buf``.  If ``nbytes`` is specified then read at most
 //|         that many bytes.  Otherwise, read at most ``len(buf)`` bytes.
 //|
diff --git a/shared-bindings/usb_midi/PortOut.c b/shared-bindings/usb_midi/PortOut.c
index b4afbc0362..92ed451e97 100644
--- a/shared-bindings/usb_midi/PortOut.c
+++ b/shared-bindings/usb_midi/PortOut.c
@@ -47,7 +47,7 @@
 
 // These are standard stream methods. Code is in py/stream.c.
 //
-//|     def write(self, buf: Any) -> Any:
+//|     def write(self, buf: ReadableBuffer) -> Optional[int]:
 //|         """Write the buffer of bytes to the bus.
 //|
 //|         :return: the number of bytes written