diff --git a/js/background.js b/js/background.js
index 42d74b8df..0788764ac 100644
--- a/js/background.js
+++ b/js/background.js
@@ -438,17 +438,24 @@
                     color: details.color,
                     active_at: activeAt,
                 })).then(function() {
-                    // this needs to be inline to get access to conversation model
-                    if (typeof details.expireTimer !== 'undefined') {
-                        var source = textsecure.storage.user.getNumber();
-                        var receivedAt = Date.now();
-                        return conversation.updateExpirationTimer(
-                            details.expireTimer,
-                            source,
-                            receivedAt,
-                            {fromSync: true}
+                    const { expireTimer } = details;
+                    const isValidExpireTimer = typeof expireTimer === 'number';
+                    if (!isValidExpireTimer) {
+                        console.log(
+                            'Ignore invalid expire timer.',
+                            'Expected numeric `expireTimer`, got:', expireTimer
                         );
+                        return;
                     }
+
+                    var source = textsecure.storage.user.getNumber();
+                    var receivedAt = Date.now();
+                    return conversation.updateExpirationTimer(
+                        expireTimer,
+                        source,
+                        receivedAt,
+                        {fromSync: true}
+                    );
                 });
             })
             .then(function() {
@@ -498,16 +505,24 @@
             }
 
             return wrapDeferred(conversation.save(updates)).then(function() {
-                if (typeof details.expireTimer !== 'undefined') {
-                    var source = textsecure.storage.user.getNumber();
-                    var receivedAt = Date.now();
-                    return conversation.updateExpirationTimer(
-                        details.expireTimer,
-                        source,
-                        receivedAt,
-                        {fromSync: true}
+                const { expireTimer } = details;
+                const isValidExpireTimer = typeof expireTimer === 'number';
+                if (!isValidExpireTimer) {
+                    console.log(
+                        'Ignore invalid expire timer.',
+                        'Expected numeric `expireTimer`, got:', expireTimer
                     );
+                    return;
                 }
+
+                var source = textsecure.storage.user.getNumber();
+                var receivedAt = Date.now();
+                return conversation.updateExpirationTimer(
+                    expireTimer,
+                    source,
+                    receivedAt,
+                    {fromSync: true}
+                );
             }).then(ev.confirm);
         });
     }
diff --git a/js/models/conversations.js b/js/models/conversations.js
index 6ed49da82..63e244ac1 100644
--- a/js/models/conversations.js
+++ b/js/models/conversations.js
@@ -707,6 +707,8 @@
         console.log(
             'Updating expireTimer for conversation',
             this.idForLogging(),
+            'to',
+            expireTimer,
             'via',
             source
         );
diff --git a/js/models/messages.js b/js/models/messages.js
index dbde2dd90..3e7ea0a70 100644
--- a/js/models/messages.js
+++ b/js/models/messages.js
@@ -457,6 +457,21 @@
                         message.set({expireTimer: dataMessage.expireTimer});
                     }
 
+                    // NOTE: Remove once the above uses
+                    // `Conversation::updateExpirationTimer`:
+                    const { expireTimer } = dataMessage;
+                    const shouldLogExpireTimerChange =
+                        message.isExpirationTimerUpdate() || expireTimer;
+                    if (shouldLogExpireTimerChange) {
+                        console.log(
+                            'Updating expireTimer for conversation',
+                            conversation.idForLogging(),
+                            'to',
+                            expireTimer,
+                            'via `handleDataMessage`'
+                        );
+                    }
+
                     if (!message.isEndSession() && !message.isGroupUpdate()) {
                         if (dataMessage.expireTimer) {
                             if (dataMessage.expireTimer !== conversation.get('expireTimer')) {