diff --git a/reactos/include/rosrtl/devmode.h b/reactos/include/rosrtl/devmode.h
index 0b6b996e6e5..7dc179d5f4c 100644
--- a/reactos/include/rosrtl/devmode.h
+++ b/reactos/include/rosrtl/devmode.h
@@ -8,6 +8,8 @@ extern "C"
 
 void
 RosRtlDevModeA2W ( LPDEVMODEW pW, const LPDEVMODEA pA );
+void
+RosRtlDevModeW2A( LPDEVMODEA pA, const LPDEVMODEW pW );
 
 #ifdef __cplusplus
 }