diff --git a/src/internet/model/global-route-manager.cc b/src/internet/model/global-route-manager.cc
index 5b42623e8..9b2cae9a5 100644
--- a/src/internet/model/global-route-manager.cc
+++ b/src/internet/model/global-route-manager.cc
@@ -25,6 +25,8 @@ NS_LOG_COMPONENT_DEFINE("GlobalRouteManager");
 //
 // ---------------------------------------------------------------------------
 
+uint32_t GlobalRouteManager::routerId = 0;
+
 void
 GlobalRouteManager::DeleteGlobalRoutes()
 {
@@ -50,7 +52,6 @@ uint32_t
 GlobalRouteManager::AllocateRouterId()
 {
     NS_LOG_FUNCTION_NOARGS();
-    static uint32_t routerId = 0;
     return routerId++;
 }
 
diff --git a/src/internet/model/global-route-manager.h b/src/internet/model/global-route-manager.h
index 1f9e145a7..1ce9edabc 100644
--- a/src/internet/model/global-route-manager.h
+++ b/src/internet/model/global-route-manager.h
@@ -59,6 +59,9 @@ class GlobalRouteManager
      * per-node forwarding tables
      */
     static void InitializeRoutes();
+
+  private:
+    static uint32_t routerId; //!< Router ID counter
 };
 
 } // namespace ns3