diff --git a/libraries/AP_NavEKF/AP_NavEKF.cpp b/libraries/AP_NavEKF/AP_NavEKF.cpp
index 6a76a6e837..a633efa804 100644
--- a/libraries/AP_NavEKF/AP_NavEKF.cpp
+++ b/libraries/AP_NavEKF/AP_NavEKF.cpp
@@ -3602,17 +3602,17 @@ void NavEKF::resetGyroBias(void)
 
 }
 
-// Commands the EKF to not use GPS. It returns true if the command has been accepted.
+// Commands the EKF to not use GPS.
 // This command must be sent prior to arming as it will only be actioned when the filter is in static mode
 // This command is forgotten by the EKF each time it goes back into static mode (eg the vehicle disarms)
+// Returns 0 if command rejected
+// Returns 1 if attitude, vertical velocity and vertical position will be provided
+// Returns 2 if attitude, 3D-velocity, vertical position and relative horizontal position will be provided
 uint8_t NavEKF::setInhibitGPS(void)
 {
-    // Ignore request if not in in static mode (when armed)
     if(!staticMode) {
         return 0;
     }
-    // If we have received flow sensor data in the last second then indicate that we can do relative position
-    // otherwise indicate we can provide attitude and height only
     if (useOptFlow()) {
         gpsInhibitMode = 2;
         return 2;
diff --git a/libraries/AP_NavEKF/AP_NavEKF.h b/libraries/AP_NavEKF/AP_NavEKF.h
index 9ff1483af8..6e7ab67ab8 100644
--- a/libraries/AP_NavEKF/AP_NavEKF.h
+++ b/libraries/AP_NavEKF/AP_NavEKF.h
@@ -114,9 +114,12 @@ public:
     // reset body axis gyro bias estimates
     void resetGyroBias(void);
 
-    // Commands the EKF to not use GPS. It returns true if the command has been accepted.
+    // Commands the EKF to not use GPS.
     // This command must be sent prior to arming as it will only be actioned when the filter is in static mode
     // This command is forgotten by the EKF each time it goes back into static mode (eg the vehicle disarms)
+    // Returns 0 if command rejected
+    // Returns 1 if attitude, vertical velocity and vertical position will be provided
+    // Returns 2 if attitude, 3D-velocity, vertical position and relative horizontal position will be provided
     uint8_t setInhibitGPS(void);
 
     // return the horizontal speed limit in m/s set by optical flow limitations