diff --git a/include/mfidl.idl b/include/mfidl.idl
index 2373e418be8..124ae3c7d2a 100644
--- a/include/mfidl.idl
+++ b/include/mfidl.idl
@@ -349,3 +349,14 @@ cpp_quote("#define MF_RESOLUTION_KEEP_BYTE_STREAM_ALIVE_ON_FAIL
 cpp_quote("#define MF_RESOLUTION_READ                                                  0x00010000")
 cpp_quote("#define MF_RESOLUTION_WRITE                                                 0x00020000")
 cpp_quote("#define MF_RESOLUTION_DISABLE_LOCAL_PLUGINS                                 0x00000040")
+
+cpp_quote("#ifdef __cplusplus")
+cpp_quote("static inline HRESULT MFSetAttributeSize(IMFAttributes *attributes, REFGUID key, UINT32 width, UINT32 height)")
+cpp_quote("{")
+cpp_quote("    return attributes->SetUINT64(key, ((UINT64)width << 32) | height);")
+cpp_quote("}")
+cpp_quote("static inline HRESULT MFSetAttributeRatio(IMFAttributes *attributes, REFGUID key, UINT32 numerator, UINT32 denominator)")
+cpp_quote("{")
+cpp_quote("    return attributes->SetUINT64(key, ((UINT64)numerator << 32) | denominator);")
+cpp_quote("}")
+cpp_quote("#endif")