diff --git a/src/tycommander/board.hpp b/src/tycommander/board.hpp
index 2ed12af..9133949 100644
--- a/src/tycommander/board.hpp
+++ b/src/tycommander/board.hpp
@@ -42,7 +42,7 @@ struct BoardInterfaceInfo {
     bool open;
 };
 
-enum RtcMode {
+enum RtcMode : int {
     RTC_LOCALTIME,
     RTC_UTC,
     RTC_IGNORE
diff --git a/src/tycommander/main_window.hpp b/src/tycommander/main_window.hpp
index 23e398f..d09aadf 100644
--- a/src/tycommander/main_window.hpp
+++ b/src/tycommander/main_window.hpp
@@ -24,7 +24,7 @@ class AboutDialog;
 class ArduinoDialog;
 class Board;
 class Monitor;
-enum RtcMode;
+enum RtcMode : int;
 
 class MainWindow : public QMainWindow, private Ui::MainWindow {
     Q_OBJECT