diff --git a/tools/scramble_korapxml.pl b/tools/scramble_korapxml.pl
index 95e727e..b20a77f 100644
--- a/tools/scramble_korapxml.pl
+++ b/tools/scramble_korapxml.pl
@@ -107,13 +107,14 @@
 # stuffed in a hash as well.
 # If no CSS rules are parsed, the file will just be copied.
 
-$rule_file = Mojo::File->new($rule_file);
+if ($rule_file) {
+  $rule_file = Mojo::File->new($rule_file);
+  if (-e $rule_file) {
+    my $rules = decode_json $rule_file->slurp;
 
-if (-e $rule_file) {
-  my $rules = decode_json $rule_file->slurp;
-
-  foreach my $rule (@$rules) {
-    scramble(@$rule);
+    foreach my $rule (@$rules) {
+      scramble(@$rule);
+    };
   };
 };