diff --git a/vncviewer/parameters.h b/vncviewer/parameters.h
index 682b6d6..9ce56b9 100644
--- a/vncviewer/parameters.h
+++ b/vncviewer/parameters.h
@@ -60,6 +60,7 @@
 extern rfb::StringParameter menuKey;
 
 extern rfb::BoolParameter fullscreenSystemKeys;
+extern rfb::BoolParameter alertOnFatalError;
 
 #ifndef WIN32
 extern rfb::StringParameter via;