diff --git a/headers/os/kernel/OS.h b/headers/os/kernel/OS.h
index 30a329059f..0ea55ce01b 100644
--- a/headers/os/kernel/OS.h
+++ b/headers/os/kernel/OS.h
@@ -374,7 +374,7 @@ extern status_t		convert_to_pthread(thread_id thread, pthread_t *_thread);
 /* Time */
 
 extern uint32		real_time_clock(void);
-extern void			set_real_time_clock(uint32 secsSinceJan1st1970);
+extern void			set_real_time_clock(uint64 secsSinceJan1st1970);
 extern bigtime_t	real_time_clock_usecs(void);
 extern bigtime_t	system_time(void);
 						/* time since booting in microseconds */
diff --git a/src/system/kernel/real_time_clock.cpp b/src/system/kernel/real_time_clock.cpp
index 8f86578726..bd2faa1e3b 100644
--- a/src/system/kernel/real_time_clock.cpp
+++ b/src/system/kernel/real_time_clock.cpp
@@ -123,7 +123,7 @@ set_real_time_clock_usecs(bigtime_t currentTime)
 
 
 void
-set_real_time_clock(uint32 currentTime)
+set_real_time_clock(uint64 currentTime)
 {
 	set_real_time_clock_usecs((bigtime_t)currentTime * 1000000);
 }
diff --git a/src/system/libroot/os/time.cpp b/src/system/libroot/os/time.cpp
index 5ba397bb1c..658ec3f843 100644
--- a/src/system/libroot/os/time.cpp
+++ b/src/system/libroot/os/time.cpp
@@ -60,7 +60,7 @@ real_time_clock_usecs(void)
 
 
 void
-set_real_time_clock(uint32 secs)
+set_real_time_clock(uint64 secs)
 {
 	_kern_set_real_time_clock((bigtime_t)secs * 1000000);
 }