diff --git a/src/util/network-monitor.hpp b/src/util/network-monitor.hpp
index b48d5e9..a9cf60b 100644
--- a/src/util/network-monitor.hpp
+++ b/src/util/network-monitor.hpp
@@ -108,7 +108,7 @@
   Signal<NetworkMonitor> onNetworkStateChanged;
 
 private:
-  std::unique_ptr<Impl> m_impl;
+  const unique_ptr<Impl> m_impl;
 };
 
 } // namespace util