diff --git a/assignment/blackbox_testing.md b/assignment/blackbox_testing.md
index 21b806ea53a1d2c0333dd56f8805a36bf29b4b8f..576d71bde9d76ee75fd255d6f41c0c0b5bb10016 100644
--- a/assignment/blackbox_testing.md
+++ b/assignment/blackbox_testing.md
@@ -139,6 +139,11 @@ stack. For example:
         should be traceable to `Calculator.calculate()`'s  functional
         requirements (listed after the assignment instructions).
 
+        -   Do *not* use the "Postfix Calculator Functional Specification."
+            This system-level specification is included for context. Your
+            testing requirements need to trace to the "`Calculator.calculate()` 
+            Functional Specification."
+
     1.  Develop the rest of the test cases in your test suite.  The test cases
         should be traceable to the testing requirements.