diff --git a/src/reverseproxy.js b/src/reverseproxy.js
index 12768818e..8aeee97b3 100644
--- a/src/reverseproxy.js
+++ b/src/reverseproxy.js
@@ -67,18 +67,18 @@ function nginxLocation(s) {
 function getCertificateDatesSync(cert) {
     assert.strictEqual(typeof cert, 'string');
 
-    const result = safe.child_process.spawnSync('/usr/bin/openssl', [ 'x509', '-startdate', '-enddate', '-noout' ], { input: cert, encoding: 'utf8' });
+    const result = safe.child_process.spawnSync('/usr/bin/openssl', [ 'x509', '-startdate', '-enddate', '-subject', '-noout' ], { input: cert, encoding: 'utf8' });
     if (!result) return { startDate: null, endDate: null } ; // some error
 
     const lines = result.stdout.trim().split('\n');
-    const notBefore = lines[1].split('=')[0];
+    const notBefore = lines[0].split('=')[1];
     const notBeforeDate = new Date(notBefore);
 
     const notAfter = lines[1].split('=')[1];
     const notAfterDate = new Date(notAfter);
 
     const daysLeft = (notAfterDate - new Date())/(24 * 60 * 60 * 1000);
-    debug(`expiryDate: notBefore=${notBefore} notAfter=${notAfter} daysLeft=${daysLeft}`);
+    debug(`expiryDate: ${lines[2]} notBefore=${notBefore} notAfter=${notAfter} daysLeft=${daysLeft}`);
 
     return { startDate: notBeforeDate, endDate: notAfterDate };
 }