diff --git a/indra/llmessage/lltransfermanager.cpp b/indra/llmessage/lltransfermanager.cpp
index ec7b21d8b60b6f3dc20d4627e08b56ca4444d9f2..452b77fb6d1f6579b9b30b6f48447f3739552ec5 100644
--- a/indra/llmessage/lltransfermanager.cpp
+++ b/indra/llmessage/lltransfermanager.cpp
@@ -62,9 +62,11 @@ LLTransferManager::LLTransferManager() :
 
 LLTransferManager::~LLTransferManager()
 {
+	// LLTransferManager should have been cleaned up by message system shutdown process
+	llassert(!mValid);
 	if (mValid)
 	{
-		LL_WARNS() << "LLTransferManager::~LLTransferManager - Should have been cleaned up by message system shutdown process" << LL_ENDL;
+		// Usually happens if OS tries to kill viewer
 		cleanup();
 	}
 }