diff --git a/internal/bridge/bridge.go b/internal/bridge/bridge.go
index 92b34f33..79453989 100644
--- a/internal/bridge/bridge.go
+++ b/internal/bridge/bridge.go
@@ -413,7 +413,7 @@ func (bridge *Bridge) Close(ctx context.Context) {
 	}
 
 	// Close all users.
-	safe.RLock(func() {
+	safe.Lock(func() {
 		for _, user := range bridge.users {
 			user.Close()
 		}
diff --git a/internal/user/user.go b/internal/user/user.go
index 8376fb61..ec010ba3 100644
--- a/internal/user/user.go
+++ b/internal/user/user.go
@@ -586,6 +586,8 @@ func (user *User) Close() {
 		for _, updateCh := range xslices.Unique(maps.Values(user.updateCh)) {
 			updateCh.CloseAndDiscardQueued()
 		}
+
+		user.updateCh = make(map[string]*async.QueuedChannel[imap.Update])
 	}, user.updateChLock)
 
 	// Close the user's notify channel.