diff --git a/libraries/AP_HAL/utility/FastDelegate.h b/libraries/AP_HAL/utility/FastDelegate.h
index 1d8fef2547..fab75df39e 100644
--- a/libraries/AP_HAL/utility/FastDelegate.h
+++ b/libraries/AP_HAL/utility/FastDelegate.h
@@ -47,7 +47,7 @@
 
 #ifndef FASTDELEGATE_H
 #define FASTDELEGATE_H
-#if _MSC_VER > 1000
+#if defined(_MSC_VER) && (_MSC_VER > 1000)
 #pragma once
 #endif // _MSC_VER > 1000