diff --git a/indra/newview/llagent.cpp b/indra/newview/llagent.cpp
index 127f0ddb6..121b300ce 100644
--- a/indra/newview/llagent.cpp
+++ b/indra/newview/llagent.cpp
@@ -2145,8 +2145,9 @@ U32 LLAgent::getControlFlags()
 //-----------------------------------------------------------------------------
 void LLAgent::setControlFlags(U32 mask)
 {
+	U32 old_flags = mControlFlags;
 	mControlFlags |= mask;
-	mbFlagsDirty = TRUE;
+	mbFlagsDirty = mControlFlags ^ old_flags;
 }