diff --git a/os/os.h b/os/os.h
index ef9f91f..ce33160 100644
--- a/os/os.h
+++ b/os/os.h
@@ -125,7 +125,11 @@
 #endif
 
 #ifndef FIO_PREFERRED_CLOCK_SOURCE
+#ifdef CONFIG_CLOCK_GETTIME
 #define FIO_PREFERRED_CLOCK_SOURCE	CS_CGETTIME
+#else
+#define FIO_PREFERRED_CLOCK_SOURCE	CS_GTOD
+#endif
 #endif
 
 #ifndef FIO_MAX_JOBS