diff --git a/internal/lsp/text_synchronization.go b/internal/lsp/text_synchronization.go
index f54ca37..d9a6961 100644
--- a/internal/lsp/text_synchronization.go
+++ b/internal/lsp/text_synchronization.go
@@ -282,6 +282,7 @@
 		// produce a better error message. The actual race to the cache should be
 		// guarded by Session.viewMu.
 		s.stateMu.Unlock()
+		close(diagnoseDone)
 		return errors.New("server is shut down")
 	}
 	s.stateMu.Unlock()
@@ -291,6 +292,7 @@
 
 	snapshots, releases, err := s.session.DidModifyFiles(ctx, modifications)
 	if err != nil {
+		close(diagnoseDone)
 		return err
 	}