--- a/dom/media/tests/mochitest/mochitest.ini
+++ b/dom/media/tests/mochitest/mochitest.ini
@@ -132,17 +132,17 @@ skip-if = os == 'android' # bug 1043403
 [test_peerConnection_capturedVideo.html]
 tags=capturestream
 skip-if = android_version == '18' # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_captureStream_canvas_2d.html]
 skip-if = (android_version == '18' && debug) # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_multiple_captureStream_canvas_2d.html]
 skip-if = (android_version == '18' && debug) # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_captureStream_canvas_webgl.html]
-# [test_peerConnection_certificates.html] # bug 1180968
+[test_peerConnection_certificates.html]
 [test_peerConnection_close.html]
 [test_peerConnection_closeDuringIce.html]
 [test_peerConnection_constructedStream.html]
 skip-if = android_version == '18' # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_errorCallbacks.html]
 [test_peerConnection_iceFailure.html]
 skip-if = os == 'linux' || os == 'mac' || os == 'win' || android_version == '18' # (Bug 1180388 for win, mac and linux), android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_insertDTMF.html]

--- a/dom/media/tests/mochitest/test_peerConnection_certificates.html
+++ b/dom/media/tests/mochitest/test_peerConnection_certificates.html
@@ -99,28 +99,28 @@
 
   var test;
   runNetworkTest(function (options) {
     var expiredCert;
     return Promise.resolve()
       .then(() => RTCPeerConnection.generateCertificate({
         name: "ECDSA",
         namedCurve: "P-256",
-        expires: 1 // smallest possible expiration window
+        expires: 0 // smallest possible expiration window
       }))
       .then(cert => {
         ok(!isNaN(cert.expires), 'cert has expiration time');
         info('Expires at ' + new Date(cert.expires));
         expiredCert = cert;
       })
 
       .then(() => checkBadParameters())
 
       .then(() => {
-        var delay = expiredCert.expires - Date.now();
+        var delay = expiredCert.expires - Date.now() + 1;
         // Hopefully this delay is never needed.
         if (delay > 0) {
           return new Promise(r => setTimeout(r, delay));
         }
       })
       .then(() => {
         ok(expiredCert.expires <= Date.now(), 'Cert should be at or past expiration');
         try {