diff --git a/library/platform_util.c b/library/platform_util.c
index 2b48f4f..d8d9708 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -181,7 +181,7 @@
     struct timespec tv;
     mbedtls_ms_time_t current_ms;
 
-    ret = clock_gettime(CLOCK_REALTIME, &tv);
+    ret = clock_gettime(CLOCK_MONOTONIC, &tv);
     if (ret) {
         return time(NULL) * 1000;
     }