diff --git a/vncviewer/parameters.h b/vncviewer/parameters.h
index d7144a4..2b4c039 100644
--- a/vncviewer/parameters.h
+++ b/vncviewer/parameters.h
@@ -60,6 +60,10 @@
 
 extern rfb::BoolParameter fullscreenSystemKeys;
 
+#ifndef WIN32
+extern rfb::StringParameter via;
+#endif
+
 void saveViewerParameters(const char *filename, const char *servername=NULL);
 char* loadViewerParameters(const char *filename);