diff --git a/ArduCopter/AP_Arming.cpp b/ArduCopter/AP_Arming.cpp
index 7e6b05d1fc..5c3bf283e4 100644
--- a/ArduCopter/AP_Arming.cpp
+++ b/ArduCopter/AP_Arming.cpp
@@ -380,7 +380,7 @@ bool AP_Arming_Copter::gps_checks(bool display_failure)
     }
 
     // warn about hdop separately - to prevent user confusion with no gps lock
-    if (copter.gps.get_hdop() > copter.g.gps_hdop_good) {
+    if ((copter.gps.num_sensors() > 0) && (copter.gps.get_hdop() > copter.g.gps_hdop_good)) {
         check_failed(ARMING_CHECK_GPS, display_failure, "High GPS HDOP");
         AP_Notify::flags.pre_arm_gps_check = false;
         return false;