diff --git a/public/js/main.js b/public/js/main.js
index 789ee50..e327ace 100644
--- a/public/js/main.js
+++ b/public/js/main.js
@@ -28,11 +28,25 @@ let certDB = null;
 let localCert = null;
 
 // Utilities
-function getCertificateChecksum(cert) {
-    let fp = cert.getFingerprints().reduce((res, curr) =>
-        curr.algorithm === 'sha-256' ? curr : res, null);
-    console.assert(fp !== null, 'Certificate does not have a sha256sum');
-    return fp.value.split(':').join('');
+function getCertificateChecksumFromSDP(desc) {
+    let fp = desc.sdp.split('\n').reduce((res, curr) =>
+        curr.startsWith('a=fingerprint:sha-256 ') ? curr : res, null);
+    console.assert(fp !== null, 'Description does not have a sha256sum');
+    return fp.trim().split(' ')[1].split(':').join('').toLowerCase();
+}
+
+async function getCertificateChecksum(cert) {
+    if (cert.getFingerprints) {
+        let fp = cert.getFingerprints().reduce((res, curr) =>
+            curr.algorithm === 'sha-256' ? curr : res, null);
+        console.assert(fp !== null, 'Certificate does not have a sha256sum');
+        return fp.value.split(':').join('');
+    } else {  // Firefox shim
+        let testConn = new RTCPeerConnection({certificates: [cert]});
+        let desc = await testConn.createOffer();
+        testConn.close();
+        return getCertificateChecksumFromSDP(desc);
+    }
 }
 
 // IndexedDB
@@ -87,8 +101,10 @@ function onLoadCert() {
     loadCertificate(certDB,
         cert => {
             if (cert !== null) {
-                console.log('Loaded certificate:', getCertificateChecksum(cert));
-                console.log('Expires:', cert.expires);
+                getCertificateChecksum(cert).then(fp => {
+                    let ts = new Date(cert.expires).toISOString();
+                    console.log(`Loaded certificate (expires ${ts}): ${fp}`);
+                });
                 localCert = cert;
                 setCertStatusDisplay('Loaded');
                 setButtonClickable('certUpload', true);
@@ -128,8 +144,10 @@ function onNewCert() {
         hash: 'SHA-256',
         namedCurve: 'P-256',
     }).then(cert => {
-        console.log('Generated new certificate:', getCertificateChecksum(cert));
-        console.log('Expires:', cert.expires);
+        getCertificateChecksum(cert).then(fp => {
+            let ts = new Date(cert.expires).toISOString();
+            console.log(`Generated new certificate (expires ${ts}): ${fp}`);
+        });
         localCert = cert;
         setCertStatusDisplay('Available');
         setButtonClickable('certUpload', true);
@@ -142,50 +160,53 @@ function onNewCert() {
 // Upload Button
 function onUploadCert() {
     console.assert(localCert !== null, 'No local certificate available');
-    fetch('/keys', {
-        method: 'POST',
-        headers: {
-            'Accept': 'application/json',
-            'Content-Type': 'application/json',
-        },
-        body: JSON.stringify({
-            'key': getCertificateChecksum(localCert),
-            'expires': localCert.expires,
-        }),
-    }).then(res => {
-        if (res.status === 200) {
-            setCertStatusDisplay('Uploaded');
-        } else {
-            res.json().then(res => {
-                setCertStatusDisplay(`Upload Failed (${res.status})`);
-            })
-        }
+    getCertificateChecksum(localCert).then(fp => {
+        fetch('/keys', {
+            method: 'POST',
+            headers: {
+                'Accept': 'application/json',
+                'Content-Type': 'application/json',
+            },
+            body: JSON.stringify({
+                'key': fp,
+                'expires': localCert.expires,
+            }),
+        }).then(res => {
+            if (res.status === 200) {
+                setCertStatusDisplay('Uploaded');
+            } else {
+                res.json().then(res => {
+                    setCertStatusDisplay(`Upload Failed (${res.status})`);
+                })
+            }
+        })
     });
 }
 
 // Clear Button
 function onClearCert() {
     console.assert(localCert !== null, 'No local certificate available');
-    let fp = getCertificateChecksum(localCert);
-    fetch(`/keys/${fp}`, {
-        method: 'DELETE',
-        headers: {
-            'Accept': 'application/json',
-            'Content-Type': 'application/json',
-        },
-    }).then(res => {
-        if (res.status === 200) {
-            setCertStatusDisplay('Cleared');
-            localCert = null;
-            setButtonClickable('certUpload', false);
-            setButtonClickable('certClear', false);
-            setButtonClickable('certSave', false);
-            setButtonClickable('chatJoin', false);
-        } else {
-            res.json().then(res => {
-                setCertStatusDisplay(`Delete Failed (${res.status})`);
-            })
-        }
+    getCertificateChecksum(localCert).then(fp => {
+        fetch(`/keys/${fp}`, {
+            method: 'DELETE',
+            headers: {
+                'Accept': 'application/json',
+                'Content-Type': 'application/json',
+            },
+        }).then(res => {
+            if (res.status === 200) {
+                setCertStatusDisplay('Cleared');
+                localCert = null;
+                setButtonClickable('certUpload', false);
+                setButtonClickable('certClear', false);
+                setButtonClickable('certSave', false);
+                setButtonClickable('chatJoin', false);
+            } else {
+                res.json().then(res => {
+                    setCertStatusDisplay(`Delete Failed (${res.status})`);
+                })
+            }
+        });
     });
 }
 
@@ -202,13 +223,6 @@ function setChatStatusDisplay(status) {
     document.getElementById('chatStatus').innerText = status;
 }
 
-function getCertificateChecksumFromSDP(desc) {
-    let fp = desc.sdp.split('\n').reduce((res, curr) =>
-        curr.startsWith('a=fingerprint:sha-256 ') ? curr : res, null);
-    console.assert(fp !== null, 'Description does not have a sha256sum');
-    return fp.trim().split(' ')[1].split(':').join('').toLowerCase();
-}
-
 function verifyFingerprint(desc) {
     let fp = getCertificateChecksumFromSDP(desc);
     fetch(`/keys/${fp}`, {
@@ -319,6 +333,9 @@ function onRTCConnectionStateChange(event) {
     let state = connection.connectionState;
 
     console.log('WebRTC connection state update:', state);
+    if (state === 'failed') {
+        onLeaveChat();
+    }
 }
 
 // Join Button