diff --git a/prism/CHANGELOG.txt b/prism/CHANGELOG.txt
index eb1fc943..19a70180 100644
--- a/prism/CHANGELOG.txt
+++ b/prism/CHANGELOG.txt
@@ -11,6 +11,7 @@ Ongoing changes:
 
 * New version of explicit engine (including extra methods e.g. for MDPs)
 * Property names allowed, but mostly not used
+* Testing mode
 
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 Version 4.0.beta2 (released 10/6/2011)