diff --git a/include/d3d10.idl b/include/d3d10.idl
index 620591773d4..ce3807bebfb 100644
--- a/include/d3d10.idl
+++ b/include/d3d10.idl
@@ -19,6 +19,7 @@
 import "oaidl.idl";
 import "ocidl.idl";
 import "dxgi.idl";
+import "d3dcommon.idl";
 
 cpp_quote("#ifndef _D3D10_CONSTANTS")
 cpp_quote("#define _D3D10_CONSTANTS")
diff --git a/include/d3dcommon.idl b/include/d3dcommon.idl
index 6cba9d2f6b0..217b3653664 100644
--- a/include/d3dcommon.idl
+++ b/include/d3dcommon.idl
@@ -35,12 +35,13 @@ typedef struct _D3D_SHADER_MACRO* LPD3D_SHADER_MACRO;
 interface ID3D10Blob : IUnknown
 {
     void *GetBufferPointer();
-    DWORD GetBufferSize();
+    SIZE_T GetBufferSize();
 }
 
 typedef ID3D10Blob* LPD3D10BLOB;
 typedef ID3D10Blob ID3DBlob;
 typedef ID3DBlob* LPD3DBLOB;
+cpp_quote("#define IID_ID3DBlob IID_ID3D10Blob")
 
 typedef enum _D3D_INCLUDE_TYPE
 {