diff --git a/src/xswiftbus/datarefs.inc b/src/xswiftbus/datarefs.inc
index 314d43911..c7c9733a8 100644
--- a/src/xswiftbus/datarefs.inc
+++ b/src/xswiftbus/datarefs.inc
@@ -1,3 +1,5 @@
+// -*- c++ -*-
+
 // DO NOT EDIT
 // This file automatically generated from DataRefs.txt by datarefs.pl
 
diff --git a/src/xswiftbus/datarefs.pl b/src/xswiftbus/datarefs.pl
index 2ba288bcd..d78a2a26e 100644
--- a/src/xswiftbus/datarefs.pl
+++ b/src/xswiftbus/datarefs.pl
@@ -87,6 +87,8 @@ close $fh;
 
 our $indent = '    ';
 print <<"EOF";
+// -*- c++ -*-
+
 // DO NOT EDIT
 // This file automatically generated from DataRefs.txt by $0