diff --git a/reactos/drivers/directx/dxapi/dxapi_driver.h b/reactos/drivers/directx/dxapi/dxapi_driver.h
index 745a4dfd620..cbe7e516dda 100644
--- a/reactos/drivers/directx/dxapi/dxapi_driver.h
+++ b/reactos/drivers/directx/dxapi/dxapi_driver.h
@@ -57,8 +57,10 @@ DWORD tblCheckInBuffer [] =
     0, // DD_DXAPI_OPENDIRECTDRAW
     0, // DD_DXAPI_OPENSURFACE
     0, // DD_DXAPI_OPENVIDEOPORT
-    0, // DD_DXAPI_GETKERNELCAPS
-    0, // DD_DXAPI_GET_VP_FIELD_NUMBER
+    /* DD_DXAPI_GETKERNELCAPS */
+    sizeof(HANDLE),
+    /* DD_DXAPI_GET_VP_FIELD_NUMBER */
+    sizeof(DDGETFIELDNUMIN),
     0, // DD_DXAPI_SET_VP_FIELD_NUMBER
     0, // DD_DXAPI_SET_VP_SKIP_FIELD
     0, // DD_DXAPI_GET_SURFACE_STATE
@@ -95,8 +97,10 @@ DWORD tblCheckOutBuffer [] =
     0, // DD_DXAPI_OPENDIRECTDRAW
     0, // DD_DXAPI_OPENSURFACE
     0, // DD_DXAPI_OPENVIDEOPORT
-    0, // DD_DXAPI_GETKERNELCAPS
-    0, // DD_DXAPI_GET_VP_FIELD_NUMBER
+    /* DD_DXAPI_GETKERNELCAPS */
+    sizeof(DDGETKERNELCAPSOUT),
+    /* DD_DXAPI_GET_VP_FIELD_NUMBER */
+    sizeof(DDGETFIELDNUMOUT),
     0, // DD_DXAPI_SET_VP_FIELD_NUMBER
     0, // DD_DXAPI_SET_VP_SKIP_FIELD
     0, // DD_DXAPI_GET_SURFACE_STATE