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+# 4.9.3
+
+* Fixed `observable.set` compatibility with IE 11, see [#1917](https://github.com/mobxjs/mobx/pull/1917) by [kalmi](https://github.com/kalmi)
+
 # 4.9.2
 
 * Fixed regression [#1878](https://github.com/mobxjs/mobx/issues/1878), accidental use of `Symbol` breaking Internet Explorer / React Native compatibility.