diff --git a/src/tex2lyx/preamble.cpp b/src/tex2lyx/preamble.cpp
index 49a8368c1b..1b97bb500f 100644
--- a/src/tex2lyx/preamble.cpp
+++ b/src/tex2lyx/preamble.cpp
@@ -482,7 +482,7 @@ void handle_package(Parser &p, string const & name, string const & opts)
 void end_preamble(ostream & os, TextClass const & /*textclass*/)
 {
 	os << "#LyX file created by tex2lyx " << PACKAGE_VERSION << "\n"
-	   << "\\lyxformat 263\n"
+	   << "\\lyxformat 264\n"
 	   << "\\begin_document\n"
 	   << "\\begin_header\n"
 	   << "\\textclass " << h_textclass << "\n";