diff --git a/src/sys/aero_time.h b/src/sys/aero_time.h
index 9911557..226fd74 100644
--- a/src/sys/aero_time.h
+++ b/src/sys/aero_time.h
@@ -19,7 +19,11 @@ inline void setupTime()
     sntp_set_time_sync_notification_cb(sync_time_cb);
     sntp_set_sync_interval(12 * 60 * 60 * 1000UL);
     String timezone = settings.getString("ntp_timezone");
-    configTzTime(timezone.c_str(), NTP_SERVER);
-    setenv("TZ", lookup_posix_timezone_tz(timezone.c_str()), 1);
-    tzset();
+    const char * tz = lookup_posix_timezone_tz(timezone.c_str());
+    if (tz != nullptr) {
+        configTzTime(tz, NTP_SERVER);
+    } else {
+        //! need to handle invalid TZ string;
+    }
+   
 }
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