diff --git a/indra/newview/aoengine.cpp b/indra/newview/aoengine.cpp
index 52f42aca30..652fbe141e 100644
--- a/indra/newview/aoengine.cpp
+++ b/indra/newview/aoengine.cpp
@@ -1793,6 +1793,45 @@ const LLUUID& AOEngine::getAOFolder() const
 
 void AOEngine::onRegionChange()
 {
+	// do nothing if the AO is off
+	if(!mEnabled)
+	{
+		return;
+	}
+
+	// catch errors without crashing
+	if(!mCurrentSet)
+	{
+		LL_DEBUGS("AOEngine") << "Current set was NULL" << LL_ENDL;
+		return;
+	}
+
+	// sitting needs special attention
+	if(mCurrentSet->getMotion()==ANIM_AGENT_SIT)
+	{
+		// do nothing if sit overrides was disabled
+		if(!mCurrentSet->getSitOverride())
+		{
+			return;
+		}
+
+		// do nothing if the last overridden motion wasn't a sit.
+		// happens when sit override is enabled but there were no
+		// sit animations added to the set yet
+		if(mLastOverriddenMotion!=ANIM_AGENT_SIT)
+		{
+			return;
+		}
+
+		// do nothing if smart sit is enabled because we have no
+		// animation running from the AO
+		if(mCurrentSet->getSmart())
+		{
+			return;
+		}
+	}
+
+	// restart current animation on region crossing
 	gAgent.sendAnimationRequest(mLastMotion,ANIM_REQUEST_START);
 }