diff --git a/src/Layout.cpp b/src/Layout.cpp
index 2700752f52..dd468258e3 100644
--- a/src/Layout.cpp
+++ b/src/Layout.cpp
@@ -875,6 +875,7 @@ docstring const i18npreamble(Language const * lang, Encoding const & enc,
 		subst(to_utf8(templ), "$$lang", lang->babel());
 
 #ifdef TEX2LYX
+	(void) enc;
 	// tex2lyx does not have getMessages()
 	LASSERT(false, /**/);
 #else