-    sensors[prefixOid.copyWithSuffix(2, idx)] = new ConstSensor<std::string>(it->first);
-    sensors[prefixOid.copyWithSuffix(3, idx)] = new ConstSensor<int>(it->second);
+    sensors[prefixOid.copyWithSuffix(2, static_cast<unsigned int>(idx))] = new ConstSensor<std::string>(it->first);
+    sensors[prefixOid.copyWithSuffix(3, static_cast<unsigned int>(idx))] = new ConstSensor<unsigned long>(it->second);