diff --git a/reactos/include/internal/hal/ddk.h b/reactos/include/internal/hal/ddk.h
index c104fadc3e3..e31bbfcae36 100644
--- a/reactos/include/internal/hal/ddk.h
+++ b/reactos/include/internal/hal/ddk.h
@@ -189,13 +189,13 @@ KdPortPutByte (UCHAR ByteToSend);
  * Port I/O functions
  */
 
-UCHAR
+VOID
 READ_PORT_BUFFER_UCHAR (PUCHAR Port, PUCHAR Value, ULONG Count);
 
-ULONG
+VOID
 READ_PORT_BUFFER_ULONG (PULONG Port, PULONG Value, ULONG Count);
 
-USHORT
+VOID
 READ_PORT_BUFFER_USHORT (PUSHORT Port, PUSHORT Value, ULONG Count);
 
 UCHAR