diff --git a/headers/os/kernel/OS.h b/headers/os/kernel/OS.h
index cfae3581b4..62ff358648 100644
--- a/headers/os/kernel/OS.h
+++ b/headers/os/kernel/OS.h
@@ -386,9 +386,6 @@ extern bigtime_t	system_time(void);
 extern nanotime_t	system_time_nsecs(void);
 						/* time since booting in nanoseconds */
 
-					/* deprecated (is no-op) */
-extern status_t		set_timezone(const char *timezone);
-
 /* Alarm */
 
 enum {
diff --git a/src/system/libroot/os/time.cpp b/src/system/libroot/os/time.cpp
index 5bf32fae7b..789c979be3 100644
--- a/src/system/libroot/os/time.cpp
+++ b/src/system/libroot/os/time.cpp
@@ -66,18 +66,6 @@ set_real_time_clock(unsigned long secs)
 }
 
 
-status_t
-set_timezone(const char* /*timezone*/)
-{
-	/* There's nothing we can do here, since we no longer support named
-	 * timezones.
-	 *
-	 * TODO: should we keep this around for compatibility or get rid of it?
-	 */
-	return ENOSYS;
-}
-
-
 bigtime_t
 set_alarm(bigtime_t when, uint32 mode)
 {
@@ -112,3 +100,13 @@ set_alarm(bigtime_t when, uint32 mode)
 	return oldInfo.remaining_time != B_INFINITE_TIMEOUT
 		? oldInfo.remaining_time : 0;
 }
+
+
+#ifdef _BEOS_R5_COMPATIBLE_
+extern "C" status_t
+set_timezone(const char* /*timezone*/)
+{
+	// There's nothing we can do here, since we no longer support named timezones.
+	return ENOSYS;
+}
+#endif