diff --git a/APMrover2/mode.h b/APMrover2/mode.h
index 906b5c2ea6..5df9c60124 100644
--- a/APMrover2/mode.h
+++ b/APMrover2/mode.h
@@ -419,7 +419,7 @@ protected:
     struct {
         uint32_t timeout_ms;// timeout from the time that guided is invoked
         float horiz_max;    // horizontal position limit in meters from where guided mode was initiated (0 = no limit)
-        uint32_t start_time;// system time in milliseconds that control was handed to the external computer
+        uint32_t start_time_ms; // system time in milliseconds that control was handed to the external computer
         Location start_loc; // starting location for checking horiz_max limit
     } limit;
 };
diff --git a/APMrover2/mode_guided.cpp b/APMrover2/mode_guided.cpp
index 429b7d720c..e57b164ee2 100644
--- a/APMrover2/mode_guided.cpp
+++ b/APMrover2/mode_guided.cpp
@@ -220,7 +220,7 @@ void ModeGuided::limit_clear()
 //  only called from AUTO mode's start_guided method
 void ModeGuided::limit_init_time_and_location()
 {
-    limit.start_time = AP_HAL::millis();
+    limit.start_time_ms = AP_HAL::millis();
     limit.start_loc = rover.current_loc;
 }
 
@@ -228,7 +228,7 @@ void ModeGuided::limit_init_time_and_location()
 bool ModeGuided::limit_breached() const
 {
     // check if we have passed the timeout
-    if ((limit.timeout_ms > 0) && (millis() - limit.start_time >= limit.timeout_ms)) {
+    if ((limit.timeout_ms > 0) && (millis() - limit.start_time_ms >= limit.timeout_ms)) {
         return true;
     }