diff --git a/extensions/sdktools/vsound.cpp b/extensions/sdktools/vsound.cpp
index 622b025e..6b161b41 100644
--- a/extensions/sdktools/vsound.cpp
+++ b/extensions/sdktools/vsound.cpp
@@ -984,6 +984,9 @@ static cell_t EmitSentence(IPluginContext *pContext, const cell_t *params)
 #endif
 		flags, 
 		pitch, 
+#if SOURCE_ENGINE == SE_ORANGEBOXVALVE
+		0, 
+#endif
 		pOrigin,
 		pDir,
 		pOrigVec,