diff --git a/firmware_handler.hpp b/firmware_handler.hpp
index fe410a1..8d41ba6 100644
--- a/firmware_handler.hpp
+++ b/firmware_handler.hpp
@@ -96,7 +96,7 @@
      * appropriately.
      */
     /** The state of the firmware update process. */
-    enum UpdateState
+    enum class UpdateState
     {
         /** The initial state. */
         notYetStarted = 0,