diff --git a/mbtk/liblynq_lib/src/lynq_time.c b/mbtk/liblynq_lib/src/lynq_time.c
index 71fd9e3..55f3ef3 100644
--- a/mbtk/liblynq_lib/src/lynq_time.c
+++ b/mbtk/liblynq_lib/src/lynq_time.c
@@ -162,6 +162,10 @@
 
 int ntp_sync_time(int enable)
 {
+    if(0 != enable && 1 != enable)
+    {
+        return -1;
+    }
     UNUSED(enable);
     int ntp_status = 0;
     if(enable)