diff --git a/src/BufferParams.cpp b/src/BufferParams.cpp
index 44573db167..f13fb287bc 100644
--- a/src/BufferParams.cpp
+++ b/src/BufferParams.cpp
@@ -474,8 +474,10 @@ string const BufferParams::readToken(Lexer & lex, string const & token,
 		string const classname = lex.getString();
 		// if there exists a local layout file, ignore the system one
 		// NOTE: in this case, the textclass (.cls file) is assumed to be available.
-		pair<bool, lyx::textclass_type> pp = textclasslist.addTextClass(
-			classname, filepath.absFilename());
+		pair<bool, lyx::textclass_type> pp;
+		if (!filepath.empty())
+			pp = textclasslist.addTextClass(
+				classname, filepath.absFilename());
 		if (pp.first)
 			setBaseClass(pp.second);
 		else {