diff --git a/question/type/calculated/upgrade.txt b/question/type/calculated/upgrade.txt
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+This file describes API changes in /question/type/calculated/*.
+
+=== 4.3 ===
+* \qtype_calculated answers are now of the type \qtype_calculated\qtype_calculated_answer which extends \qtype_numerical_answer.
+  Plugins extending \qtype_calculated and still reference \qtype_numerical_answer in their code (e.g. in test helper functions)
+  should update their code to reference \qtype_calculated\qtype_calculated_answer instead.