diff --git a/src/dock_gui.cpp b/src/dock_gui.cpp
--- a/src/dock_gui.cpp
+++ b/src/dock_gui.cpp
@@ -306,7 +306,7 @@ static const WindowDesc _build_docks_too
 
 void ShowBuildDocksToolbar()
 {
-	if (!IsValidCompanyID(_local_company)) return;
+	if (!Company::IsValidID(_local_company)) return;
 
 	DeleteWindowByClass(WC_BUILD_TOOLBAR);
 	AllocateWindowDescFront<BuildDocksToolbarWindow>(&_build_docks_toolbar_desc, TRANSPORT_WATER);