diff --git a/autotests/chatbarcachetest.cpp b/autotests/chatbarcachetest.cpp
index 198ccc555..fee7270e9 100644
--- a/autotests/chatbarcachetest.cpp
+++ b/autotests/chatbarcachetest.cpp
@@ -6,6 +6,7 @@
 #include <QObject>
 #include <QTest>
 
+#include <QSignalSpy>
 #include <Quotient/roommember.h>
 #include <Quotient/syncdata.h>
 #include <qtestcase.h>
@@ -32,6 +33,7 @@ private Q_SLOTS:
     void noRoom();
     void badParent();
     void reply();
+    void replyMissingUser();
     void edit();
     void attachment();
 };
@@ -102,6 +104,33 @@ void ChatBarCacheTest::reply()
     QCOMPARE(chatBarCache->relationAuthor(), room->member(u"@example:example.org"_s));
     QCOMPARE(chatBarCache->relationMessage(), u"This is an example\ntext message"_s);
     QCOMPARE(chatBarCache->attachmentPath(), QString());
+    QCOMPARE(chatBarCache->relationAuthorIsPresent(), true);
+}
+
+void ChatBarCacheTest::replyMissingUser()
+{
+    QScopedPointer<ChatBarCache> chatBarCache(new ChatBarCache(room));
+    chatBarCache->setText(u"some text"_s);
+    chatBarCache->setAttachmentPath(u"some/path"_s);
+    chatBarCache->setReplyId(u"$153456789:example.org"_s);
+
+    QCOMPARE(chatBarCache->text(), u"some text"_s);
+    QCOMPARE(chatBarCache->isReplying(), true);
+    QCOMPARE(chatBarCache->replyId(), u"$153456789:example.org"_s);
+    QCOMPARE(chatBarCache->isEditing(), false);
+    QCOMPARE(chatBarCache->editId(), QString());
+    QCOMPARE(chatBarCache->relationAuthor(), room->member(u"@example:example.org"_s));
+    QCOMPARE(chatBarCache->relationMessage(), u"This is an example\ntext message"_s);
+    QCOMPARE(chatBarCache->attachmentPath(), QString());
+    QCOMPARE(chatBarCache->relationAuthorIsPresent(), true);
+
+    QSignalSpy relationAuthorIsPresentSpy(chatBarCache.get(), &ChatBarCache::relationAuthorIsPresentChanged);
+
+    // sync again, which will simulate the reply user leaving the room
+    room->syncNewEvents(u"test-min-sync-extra-sync.json"_s);
+
+    QTRY_COMPARE(relationAuthorIsPresentSpy.count(), 1);
+    QCOMPARE(chatBarCache->relationAuthorIsPresent(), false);
 }
 
 void ChatBarCacheTest::edit()
diff --git a/autotests/data/test-min-sync-extra-sync.json b/autotests/data/test-min-sync-extra-sync.json
new file mode 100644
index 000000000..52453b21b
--- /dev/null
+++ b/autotests/data/test-min-sync-extra-sync.json
@@ -0,0 +1,20 @@
+{
+  "state": {
+    "events": [
+      {
+        "content": {
+          "membership": "leave"
+        },
+        "event_id": "$1432735824666PhrSA:example.org",
+        "origin_server_ts": 1432735824666,
+        "room_id": "!jEsUZKDJdhlrceRyVU:example.org",
+        "sender": "@example:example.org",
+        "state_key": "@example:example.org",
+        "type": "m.room.member",
+        "unsigned": {
+          "replaces_state": "$143273582443PhrSn:example.org"
+        }
+      }
+    ]
+  }
+}
diff --git a/src/chatbar/ChatBar.qml b/src/chatbar/ChatBar.qml
index 8503ac324..93e541895 100644
--- a/src/chatbar/ChatBar.qml
+++ b/src/chatbar/ChatBar.qml
@@ -197,6 +197,22 @@ QQC2.Control {
             visible: root.currentRoom.mainCache.replyId.length > 0
             sourceComponent: replyPane
         }
+        RowLayout {
+            visible: replyLoader.visible && !root.currentRoom.mainCache.relationAuthorIsPresent
+            spacing: Kirigami.Units.smallSpacing
+
+            Kirigami.Icon {
+                source: "help-hint-symbolic"
+                color: Kirigami.Theme.disabledTextColor
+
+                Layout.preferredWidth: Kirigami.Units.iconSizes.small
+                Layout.preferredHeight: Kirigami.Units.iconSizes.small
+            }
+            QQC2.Label {
+                text: i18nc("@info", "The user you're replying to has left the room, and can't be notified.")
+                color: Kirigami.Theme.disabledTextColor
+            }
+        }
         Loader {
             id: attachLoader
 
diff --git a/src/libneochat/chatbarcache.cpp b/src/libneochat/chatbarcache.cpp
index 234e64d28..12799b4c8 100644
--- a/src/libneochat/chatbarcache.cpp
+++ b/src/libneochat/chatbarcache.cpp
@@ -15,6 +15,18 @@ using namespace Qt::StringLiterals;
 ChatBarCache::ChatBarCache(QObject *parent)
     : QObject(parent)
 {
+    if (parent == nullptr) {
+        qWarning() << "ChatBarCache created with no parent, a NeoChatRoom must be set as the parent on creation.";
+        return;
+    }
+    auto room = dynamic_cast<NeoChatRoom *>(parent);
+    if (room == nullptr) {
+        qWarning() << "ChatBarCache created with incorrect parent, a NeoChatRoom must be set as the parent on creation.";
+        return;
+    }
+    connect(room, &NeoChatRoom::memberLeft, this, &ChatBarCache::relationAuthorIsPresentChanged);
+    connect(room, &NeoChatRoom::memberJoined, this, &ChatBarCache::relationAuthorIsPresentChanged);
+    connect(this, &ChatBarCache::relationIdChanged, this, &ChatBarCache::relationAuthorIsPresentChanged);
 }
 
 QString ChatBarCache::text() const
@@ -137,6 +149,11 @@ Quotient::RoomMember ChatBarCache::relationAuthor() const
     return room->member((*room->findInTimeline(m_relationId))->senderId());
 }
 
+bool ChatBarCache::relationAuthorIsPresent() const
+{
+    return relationAuthor().membershipState() == Quotient::Membership::Join;
+}
+
 QString ChatBarCache::relationMessage() const
 {
     if (parent() == nullptr) {
diff --git a/src/libneochat/chatbarcache.h b/src/libneochat/chatbarcache.h
index be89e36f1..2d19811a6 100644
--- a/src/libneochat/chatbarcache.h
+++ b/src/libneochat/chatbarcache.h
@@ -99,6 +99,13 @@ class ChatBarCache : public QObject
      */
     Q_PROPERTY(Quotient::RoomMember relationAuthor READ relationAuthor NOTIFY relationIdChanged)
 
+    /**
+     * @brief If the author for the message being replied to is still present in the room.
+     *
+     * @sa Quotient::RoomMember
+     */
+    Q_PROPERTY(bool relationAuthorIsPresent READ relationAuthorIsPresent NOTIFY relationAuthorIsPresentChanged)
+
     /**
      * @brief The content of the related message.
      *
@@ -153,6 +160,7 @@ public:
     void setEditId(const QString &editId);
 
     Quotient::RoomMember relationAuthor() const;
+    bool relationAuthorIsPresent() const;
 
     QString relationMessage() const;
 
@@ -196,6 +204,7 @@ Q_SIGNALS:
     void threadIdChanged(const QString &oldThreadId, const QString &newThreadId);
     void attachmentPathChanged();
     void mentionAdded(const QString &mention);
+    void relationAuthorIsPresentChanged();
 
 private:
     QString m_text = QString();