diff --git a/sdk-api-src/content/d3d9/nf-d3d9-idirect3dresource9-getprivatedata.md b/sdk-api-src/content/d3d9/nf-d3d9-idirect3dresource9-getprivatedata.md
index 13ffb84bd233..df2fa4f5771f 100644
--- a/sdk-api-src/content/d3d9/nf-d3d9-idirect3dresource9-getprivatedata.md
+++ b/sdk-api-src/content/d3d9/nf-d3d9-idirect3dresource9-getprivatedata.md
@@ -97,6 +97,8 @@ This method is inherited by the following interfaces:
   
 <a href="/windows/desktop/api/d3d9helper/nn-d3d9helper-idirect3dvertexbuffer9">IDirect3DVertexBuffer9</a>.
 
+If the data returned is a pointer to an <a href="/windows/desktop/api/unknwn/nn-unknwn-iunknown">IUnknown</a>, or one of its derivative classes, which was previously set by **SetPrivateData** with a `D3DSPD_IUNKNOWN` flag, that interface will have its reference count incremented before the private data is returned.
+
 ## -see-also
 
 <a href="/windows/desktop/api/d3d9helper/nn-d3d9helper-idirect3dresource9">IDirect3DResource9</a>