diff --git a/DDrawCompat/D3dDdi/KernelModeThunks.cpp b/DDrawCompat/D3dDdi/KernelModeThunks.cpp
index 61b905c..d1073b5 100644
--- a/DDrawCompat/D3dDdi/KernelModeThunks.cpp
+++ b/DDrawCompat/D3dDdi/KernelModeThunks.cpp
@@ -161,7 +161,7 @@ namespace
 		{
 			return -1;
 		}
-		return data.ScanLine;
+		return data.InVerticalBlank ? 0 : data.ScanLine;
 	}
 
 	void getVidPnSource(D3DKMT_HANDLE& adapter, UINT& vidPnSourceId)