diff --git a/core/fiber/storage_spec.rb b/core/fiber/storage_spec.rb
index d5603f006..a461ca732 100644
--- a/core/fiber/storage_spec.rb
+++ b/core/fiber/storage_spec.rb
@@ -96,8 +96,7 @@
       it "can use keys as strings" do
         key = Object.new
         def key.to_str; "Foo"; end
-        Fiber[key] = 42
-        Fiber["Foo"].should == 42
+        Fiber.new { Fiber[key] = 42; Fiber["Foo"] }.resume.should == 42
       end
     end