diff --git a/libraries/AP_GPS/AP_GPS_Shim.h b/libraries/AP_GPS/AP_GPS_Shim.h
index 38ffc7c568..feef923690 100644
--- a/libraries/AP_GPS/AP_GPS_Shim.h
+++ b/libraries/AP_GPS/AP_GPS_Shim.h
@@ -30,7 +30,7 @@ public:
     /// defines a member function set_<variable>(<type>)
     ///
 #define __GPS_SHIM_SET(__type, __name) void set_##__name(__type v) { __name = v; _updated = true; }
-    __GPS_SHIM_SET(long, time);
+    __GPS_SHIM_SET(uint32_t, time);
     __GPS_SHIM_SET(long, latitude);
     __GPS_SHIM_SET(long, longitude);
     __GPS_SHIM_SET(long, altitude);
diff --git a/libraries/AP_GPS/GPS.h b/libraries/AP_GPS/GPS.h
index 1638d76a8c..e0b2a59b15 100644
--- a/libraries/AP_GPS/GPS.h
+++ b/libraries/AP_GPS/GPS.h
@@ -75,7 +75,7 @@ public:
     virtual void	init(void) = 0;
 
     // Properties
-    long	time;			///< GPS time (milliseconds from epoch)
+    uint32_t time;			///< GPS time (milliseconds from epoch)
     long	date;			///< GPS date (FORMAT TBD)
     long	latitude;		///< latitude in degrees * 10,000,000
     long	longitude;		///< longitude in degrees * 10,000,000