diff --git a/TOOLS/matroska.pl b/TOOLS/matroska.pl
index 3ab06df6f9..4eda2de44f 100755
--- a/TOOLS/matroska.pl
+++ b/TOOLS/matroska.pl
@@ -101,7 +101,7 @@ sub generate_c_definitions {
 
             # define a field for each subelement
             # also does lots of macro magic, but doesn't open a scope
-            for my $subel (values %{$el->{subelements}}) {
+            for my $subel (sort { $a->{definename} cmp $b->{definename} } values %{$el->{subelements}}) {
                 print "F($subel->{definename}, $subel->{fieldname}, ".
                     ($subel->{multiple}?'1':'0').")\n";
             }
@@ -166,4 +166,4 @@ sub process_elem {
     } else {
         print "$elem->{type} ". $elem->get_value ."\n";
     }
-}
\ No newline at end of file
+}