diff --git a/tools/simulators.hpp b/tools/simulators.hpp
index c52fea5..3b373af 100644
--- a/tools/simulators.hpp
+++ b/tools/simulators.hpp
@@ -18,6 +18,6 @@ class Simulators {
         json changed_UI_items();
     private:
         std::map<std::string, std::unique_ptr<Simulator_base>> m_simulators;
-        std::string m_current_simulator;
+        std::string m_current_simulator = "";
         json m_before;
 };
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