diff --git a/servers/puppet/modules/zulip/files/nagios_plugins/check_personal_zephyr_mirrors b/servers/puppet/modules/zulip/files/nagios_plugins/check_personal_zephyr_mirrors
index 5c0b502efc..11dabd8054 100644
--- a/servers/puppet/modules/zulip/files/nagios_plugins/check_personal_zephyr_mirrors
+++ b/servers/puppet/modules/zulip/files/nagios_plugins/check_personal_zephyr_mirrors
@@ -32,7 +32,10 @@ for results_file_name in os.listdir(RESULTS_DIR):
     data = file(results_file).read().strip()
     last_check = os.stat(results_file).st_mtime
     time_since_last_check = time.time() - last_check
-    if data.split("\n")[-1].strip() == "0" and time_since_last_check < 60:
+    # time_since_last_check threshhold needs to be strictly greater
+    # than 1 minute, since with cron we expect intervals of at least 1
+    # minute without any update
+    if data.split("\n")[-1].strip() == "0" and time_since_last_check < 90:
         this_state = "OK"
     else:
         this_state = "CRITICAL"