diff --git a/src/xbus/main.cpp b/src/xbus/main.cpp
index e84619c15..3f7241525 100644
--- a/src/xbus/main.cpp
+++ b/src/xbus/main.cpp
@@ -3,7 +3,9 @@
  *  License, v. 2.0. If a copy of the MPL was not distributed with this
  *  file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif
 #include "plugin.h"
 #include "utils.h"
 #include "traffic.h"
diff --git a/src/xbus/plugin.h b/src/xbus/plugin.h
index 7341bc36e..2a45ef93f 100644
--- a/src/xbus/plugin.h
+++ b/src/xbus/plugin.h
@@ -13,7 +13,9 @@
  * Plugin loaded by X-Plane which publishes a DBus service
  */
 
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif
 #include "menus.h"
 
 #pragma push_macro("interface")
diff --git a/src/xbus/service.h b/src/xbus/service.h
index e15316635..89eb429f7 100644
--- a/src/xbus/service.h
+++ b/src/xbus/service.h
@@ -8,7 +8,9 @@
 
 //! \file
 
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif
 #include "datarefs.h"
 #include "blackmisc/geodesicgrid.h"
 #include <XPLM/XPLMNavigation.h>
diff --git a/src/xbus/traffic.cpp b/src/xbus/traffic.cpp
index a098154d2..0f05ed458 100644
--- a/src/xbus/traffic.cpp
+++ b/src/xbus/traffic.cpp
@@ -3,7 +3,9 @@
  *  License, v. 2.0. If a copy of the MPL was not distributed with this
  *  file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#ifndef NOMINMAX
 #define NOMINMAX
+#endif
 #include "traffic.h"
 #include "XPMPMultiplayer.h"
 #include <XPLM/XPLMProcessing.h>