1 files changed, 1 insertions, 1 deletions
diff --git a/lib/test/unit/assertions.rb b/lib/test/unit/assertions.rb
index 234775f1a3..a06962fceb 100644
--- a/lib/test/unit/assertions.rb
+++ b/lib/test/unit/assertions.rb
@@ -13,7 +13,7 @@ module Test
       def assert(test, msg = (nomsg = true; nil))
         unless nomsg or msg.instance_of?(String) or msg.instance_of?(Proc) or
             (bt = caller).shift.rindex(MiniTest::MINI_DIR, 0)
-          bt = MiniTest.delete_if {|s| rindex(MiniTest::MINI_DIR, 0)}
+          bt.delete_if {|s| s.rindex(MiniTest::MINI_DIR, 0)}
           raise ArgumentError, "assertion message must be String or Proc, but #{msg.class} was given.", bt
         end
         super