diff --git a/libraries/AP_GPS/GPS_Backend.cpp b/libraries/AP_GPS/GPS_Backend.cpp
index b6379abde3..89cff87262 100644
--- a/libraries/AP_GPS/GPS_Backend.cpp
+++ b/libraries/AP_GPS/GPS_Backend.cpp
@@ -17,7 +17,7 @@
 #include "GPS_Backend.h"
 #include <AP_Logger/AP_Logger.h>
 #include <time.h>
-#include <AP_RTC/AP_RTC.h>
+#include <AP_Common/time.h>
 #include <AP_InternalError/AP_InternalError.h>
 
 #define GPS_BACKEND_DEBUGGING 0
@@ -96,7 +96,7 @@ void AP_GPS_Backend::make_gps_time(uint32_t bcd_date, uint32_t bcd_milliseconds)
     tm.tm_hour = v % 100U;
 
     // convert from time structure to unix time
-    time_t unix_time = AP::rtc().mktime(&tm);
+    time_t unix_time = ap_mktime(&tm);
 
     // convert to time since GPS epoch
     const uint32_t unix_to_GPS_secs = 315964800UL;