diff --git a/indra/media_plugins/cef/media_plugin_cef.cpp b/indra/media_plugins/cef/media_plugin_cef.cpp
index c497a96cdcf7b4b5d20b4796ad32f731a80bcb3a..1942b3d80c4c6c9df64a445cf710d5df6317a25e 100644
--- a/indra/media_plugins/cef/media_plugin_cef.cpp
+++ b/indra/media_plugins/cef/media_plugin_cef.cpp
@@ -72,6 +72,7 @@ class MediaPluginCEF :
 	bool onHTTPAuthCallback(const std::string host, const std::string realm, std::string& username, std::string& password);
 	void onCursorChangedCallback(dullahan::ECursorType type);
 	const std::vector<std::string> onFileDialog(dullahan::EFileDialogType dialog_type, const std::string dialog_title, const std::string default_file, const std::string dialog_accept_filter, bool& use_default);
+	bool onJSDialogCallback(const std::string origin_url, const std::string message_text, const std::string default_prompt_text);
 
 	void postDebugMessage(const std::string& msg);
 	void authResponse(LLPluginMessage &message);
@@ -360,6 +361,14 @@ const std::vector<std::string> MediaPluginCEF::onFileDialog(dullahan::EFileDialo
 	return std::vector<std::string>();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+//
+bool MediaPluginCEF::onJSDialogCallback(const std::string origin_url, const std::string message_text, const std::string default_prompt_text)
+{
+	// return true indicates we suppress the JavaScript alert UI entirely
+	return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 //
 void MediaPluginCEF::onCursorChangedCallback(dullahan::ECursorType type)
@@ -506,6 +515,7 @@ void MediaPluginCEF::receiveMessage(const char* message_string)
 				mCEFLib->setOnFileDialogCallback(std::bind(&MediaPluginCEF::onFileDialog, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4, std::placeholders::_5));
 				mCEFLib->setOnCursorChangedCallback(std::bind(&MediaPluginCEF::onCursorChangedCallback, this, std::placeholders::_1));
 				mCEFLib->setOnRequestExitCallback(std::bind(&MediaPluginCEF::onRequestExitCallback, this));
+				mCEFLib->setOnJSDialogCallback(std::bind(&MediaPluginCEF::onJSDialogCallback, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));
 
 				dullahan::dullahan_settings settings;
 				settings.accept_language_list = mHostLanguage;