diff --git a/lib/Directory/Simplify/Instruction/Generator.pm b/lib/Directory/Simplify/Instruction/Generator.pm
index 4f6c2ac..fdbd1d8 100644
--- a/lib/Directory/Simplify/Instruction/Generator.pm
+++ b/lib/Directory/Simplify/Instruction/Generator.pm
@@ -87,11 +87,12 @@ sub _entries_are_hard_linkable {
     return 0;
 }
 
-sub oldest_mtime {
-    my $self = shift;
-    return sort {
+sub _oldest_mtime {
+    my @entries = @_;
+    my @sorted = sort {
         $a->{mtime} <=> $b->{mtime}
-    } @_;
+    } @entries;
+    return @sorted;
 }
 
 sub more_linked {
@@ -149,7 +150,7 @@ sub instructions {
     foreach my $bucket ($self->buckets) {
 
         # of the bucket, find the oldest timestamp
-        my ($oldest_entry) = $self->oldest_mtime(@{$bucket});
+        my ($oldest_entry) = _oldest_mtime(@{$bucket});
 
         # of the bucket, find the file most embedded in the file system
         my @to_link = $self->more_linked(@{$bucket});