diff --git a/index.js b/index.js
index 3d0f480..281d9ba 100644
--- a/index.js
+++ b/index.js
@@ -1,13 +1,14 @@
 'use strict';
 
 var DAY = 24 * 60 * 60 * 1000;
+var HOUR = 60 * 60 * 1000;
 var MIN = 60 * 1000;
 var defaults = {
   // don't renew before the renewWithin period
   renewWithin: 14 * DAY
-, _renewWithinMin: 10 * DAY
+, _renewWithinMin: 3 * DAY
   // renew before the renewBy period
-, renewBy: 2 * DAY
+, renewBy: 10 * DAY
 , _renewByMin: Math.floor(DAY / 2)
   // just to account for clock skew really
 , _dropDead: 5 * MIN
@@ -19,11 +20,11 @@ module.exports.create = function (autoSni) {
   if (!autoSni.getCertificatesAsync) { autoSni.getCertificatesAsync = require('bluebird').promisify(autoSni.getCertificates); }
   if (!autoSni.renewWithin) { autoSni.renewWithin = autoSni.notBefore || defaults.renewWithin; }
   if (autoSni.renewWithin < defaults._renewWithinMin) {
-    throw new Error("options.renewWithin should be at least 3 days");
+    throw new Error("options.renewWithin should be at least " + (defaults._renewWithinMin / DAY) + " days");
   }
   if (!autoSni.renewBy) { autoSni.renewBy = autoSni.notAfter || defaults.renewBy; }
   if (autoSni.renewBy < defaults._renewByMin) {
-    throw new Error("options.renewBy should be at least 12 hours");
+    throw new Error("options.renewBy should be at least " + (defaults._renewBy / HOUR) + " hours");
   }
   if (!autoSni.tlsOptions) { autoSni.tlsOptions = autoSni.httpsOptions || {}; }