diff --git a/lib/minitest.rb b/lib/minitest.rb
index 5525ade1..52fccceb 100644
--- a/lib/minitest.rb
+++ b/lib/minitest.rb
@@ -231,7 +231,9 @@ def self.process_args args = [] # :nodoc:
   end
 
   def self.filter_backtrace bt # :nodoc:
-    backtrace_filter.filter bt
+    new_bt = backtrace_filter.filter bt
+    new_bt = bt.dup if new_bt.empty?
+    new_bt
   end
 
   ##
@@ -818,7 +820,6 @@ def filter bt
 
       new_bt = bt.take_while { |line| line !~ mt_re }
       new_bt = bt.select     { |line| line !~ mt_re } if new_bt.empty?
-      new_bt = bt.dup                                 if new_bt.empty?
 
       new_bt
     end