diff --git a/reactos/include/ddk/ioaccess.h b/reactos/include/ddk/ioaccess.h
index 547422246aa..677b9f4086c 100755
--- a/reactos/include/ddk/ioaccess.h
+++ b/reactos/include/ddk/ioaccess.h
@@ -38,9 +38,9 @@ extern "C" {
 #define WRITE_REGISTER_UCHAR(r, v) (*(volatile UCHAR *)(r) = (v))
 #define WRITE_REGISTER_USHORT(r, v) (*(volatile USHORT *)(r) = (v))
 #define WRITE_REGISTER_ULONG(r, v) (*(volatile ULONG *)(r) = (v))
-#define READ_PORT_UCHAR(p) (UCHAR)(__inbyte H2I(p))
-#define READ_PORT_USHORT(p) (USHORT)(__inword H2I(p))
-#define READ_PORT_ULONG(p) (ULONG)(__indword H2I(p))
+#define READ_PORT_UCHAR(p) (UCHAR)(__inbyte (H2I(p)))
+#define READ_PORT_USHORT(p) (USHORT)(__inword (H2I(p)))
+#define READ_PORT_ULONG(p) (ULONG)(__indword (H2I(p)))
 #define WRITE_PORT_UCHAR(p, v) __outbyte (H2I(p), (v))
 #define WRITE_PORT_USHORT(p, v) __outword (H2I(p), (v))
 #define WRITE_PORT_ULONG(p, v) __outdword (H2I(p), (v))