diff --git a/src/bionics.h b/src/bionics.h
index 5080989ea378e..5ef1a76fc7ebd 100644
--- a/src/bionics.h
+++ b/src/bionics.h
@@ -131,7 +131,7 @@ struct bionic_data {
 
     bool is_included( const bionic_id &id ) const;
 
-    bool was_loaded;
+    bool was_loaded = false;
     void load( const JsonObject &obj, std::string );
     static void load_bionic( const JsonObject &jo, const std::string &src );
     static const std::vector<bionic_data> &get_all();