diff --git a/include/strmif.idl b/include/strmif.idl
index a1cad6ba00e..a06f99b7517 100644
--- a/include/strmif.idl
+++ b/include/strmif.idl
@@ -16,6 +16,7 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
+import "unknwn.idl";
 import "objidl.idl";
 
 #include <devenum.idl>