diff --git a/src/core/js/ext_revisions.js b/src/core/js/ext_revisions.js
index 59aaa698ccda220b17c2b439b685bfd0dbe0a511..3ee086e60ed34ac659c5bb92de71d78b38f30e2b 100644
--- a/src/core/js/ext_revisions.js
+++ b/src/core/js/ext_revisions.js
@@ -31,7 +31,7 @@
  * proxy (or wrapper) function adds further functionality.
  *
  * The extended update function creates a back-up version of the updated entity
- * and and adds a revisionOf property to the updated entity which references
+ * and adds a revisionOf property to the updated entity which references
  * the back-up. The back-up entity loses all of its original parents and gets
  * an "Obsolete" as only parent instead.
  *