diff --git a/src/mapport.cpp b/src/mapport.cpp
--- a/src/mapport.cpp
+++ b/src/mapport.cpp
@@ -36,6 +36,10 @@
 #ifdef USE_UPNP
 static CThreadInterrupt g_upnp_interrupt;
 static std::thread g_upnp_thread;
+
+using namespace std::chrono_literals;
+static constexpr auto PORT_MAPPING_REANNOUNCE_PERIOD{20min};
+
 static void ThreadMapPort() {
     std::string port = strprintf("%u", GetListenPort());
     const char *multicastif = nullptr;
@@ -90,7 +94,7 @@
             } else {
                 LogPrintf("UPnP Port Mapping successful.\n");
             }
-        } while (g_upnp_interrupt.sleep_for(std::chrono::minutes(20)));
+        } while (g_upnp_interrupt.sleep_for(PORT_MAPPING_REANNOUNCE_PERIOD));
 
         r = UPNP_DeletePortMapping(urls.controlURL, data.first.servicetype,
                                    port.c_str(), "TCP", 0);