diff --git a/src/reverseproxy.js b/src/reverseproxy.js
index 3b06f58d7..12768818e 100644
--- a/src/reverseproxy.js
+++ b/src/reverseproxy.js
@@ -255,7 +255,7 @@ function getAcmeCertificateNameSync(fqdn, domainObject) {
 
 function needsRenewalSync(cert, options) {
     assert.strictEqual(typeof cert, 'string');
-    assert.strictEqual(typeof options, 'string');
+    assert.strictEqual(typeof options, 'object');
 
     const { startDate, endDate } = getCertificateDatesSync(cert);
     const now = new Date();