diff --git a/libraries/AP_Button/AP_Button.h b/libraries/AP_Button/AP_Button.h
index 8034899613..a0c2903cd2 100644
--- a/libraries/AP_Button/AP_Button.h
+++ b/libraries/AP_Button/AP_Button.h
@@ -12,6 +12,7 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#pragma once
 
 #include <AP_HAL/AP_HAL.h>
 #include <AP_Param/AP_Param.h>