diff --git a/libraries/AP_Common/c++.cpp b/libraries/AP_Common/c++.cpp
index a60834d0b9..1eac70d0c8 100644
--- a/libraries/AP_Common/c++.cpp
+++ b/libraries/AP_Common/c++.cpp
@@ -1,4 +1,4 @@
-// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
 
 //
 // C++ runtime support not provided by Arduino