diff --git a/3rdparty/boost/boost/function/detail/gen_maybe_include.pl b/3rdparty/boost/boost/function/detail/gen_maybe_include.pl
index d0629205e1..982b91db37 100644
--- a/3rdparty/boost/boost/function/detail/gen_maybe_include.pl
+++ b/3rdparty/boost/boost/function/detail/gen_maybe_include.pl
@@ -1,4 +1,5 @@
 #!/usr/bin/perl -w
+# -*- mode: perl; -*-
 #
 # Boost.Function library
 #
diff --git a/3rdparty/boost/boost/function/gen_function_N.pl b/3rdparty/boost/boost/function/gen_function_N.pl
index d8f1249b07..c2fb318dc2 100644
--- a/3rdparty/boost/boost/function/gen_function_N.pl
+++ b/3rdparty/boost/boost/function/gen_function_N.pl
@@ -1,4 +1,5 @@
 #!/usr/bin/perl -w
+# -*- mode: perl; -*-
 #
 # Boost.Function library
 #
diff --git a/development/cmake/doc/ReplaceValues.pl b/development/cmake/doc/ReplaceValues.pl
index d3bd8139e6..652cb0dcfd 100644
--- a/development/cmake/doc/ReplaceValues.pl
+++ b/development/cmake/doc/ReplaceValues.pl
@@ -1,4 +1,5 @@
 #! /usr/bin/env perl
+# -*- mode: perl; -*-
 
 use strict;
 
diff --git a/po/pocheck.pl b/po/pocheck.pl
index 68dd83f23c..1cd3a8c94e 100755
--- a/po/pocheck.pl
+++ b/po/pocheck.pl
@@ -1,4 +1,5 @@
 #! /usr/bin/perl -w
+# -*- mode: perl; -*-
 
 # file pocheck.pl
 #