diff --git a/internal/lsp/command.go b/internal/lsp/command.go
index a622329bf8..20ae57faeb 100644
--- a/internal/lsp/command.go
+++ b/internal/lsp/command.go
@@ -235,7 +235,7 @@ func (s *Server) runCommand(ctx context.Context, work *workDone, command *source
 		}
 		snapshot, release := sv.Snapshot(ctx)
 		defer release()
-		s.diagnoseSnapshot(snapshot, nil)
+		s.diagnoseSnapshot(snapshot, nil, false)
 	case source.CommandGenerateGoplsMod:
 		var v source.View
 		if len(args) == 0 {
diff --git a/internal/lsp/diagnostics.go b/internal/lsp/diagnostics.go
index f878108656..c54bdaaf91 100644
--- a/internal/lsp/diagnostics.go
+++ b/internal/lsp/diagnostics.go
@@ -82,7 +82,7 @@ func (s *Server) diagnoseDetached(snapshot source.Snapshot) {
 	s.publishReports(ctx, snapshot, reports, false)
 }
 
-func (s *Server) diagnoseSnapshot(snapshot source.Snapshot, changedURIs []span.URI) {
+func (s *Server) diagnoseSnapshot(snapshot source.Snapshot, changedURIs []span.URI, onDisk bool) {
 	ctx := snapshot.View().BackgroundContext()
 
 	delay := snapshot.View().Options().ExperimentalDiagnosticsDelay
@@ -93,7 +93,7 @@ func (s *Server) diagnoseSnapshot(snapshot source.Snapshot, changedURIs []span.U
 		// by file modifications (no analysis).
 		//
 		// The second phase does everything, and is debounced by the configured delay.
-		reports, err := s.diagnoseChangedFiles(ctx, snapshot, changedURIs)
+		reports, err := s.diagnoseChangedFiles(ctx, snapshot, changedURIs, onDisk)
 		if err != nil {
 			if !errors.Is(err, context.Canceled) {
 				event.Error(ctx, "diagnosing changed files", err)
@@ -112,11 +112,16 @@ func (s *Server) diagnoseSnapshot(snapshot source.Snapshot, changedURIs []span.U
 	s.publishReports(ctx, snapshot, reports, false)
 }
 
-func (s *Server) diagnoseChangedFiles(ctx context.Context, snapshot source.Snapshot, uris []span.URI) (*reportSet, error) {
+func (s *Server) diagnoseChangedFiles(ctx context.Context, snapshot source.Snapshot, uris []span.URI, onDisk bool) (*reportSet, error) {
 	ctx, done := event.Start(ctx, "Server.diagnoseChangedFiles")
 	defer done()
 	packages := make(map[source.Package]struct{})
 	for _, uri := range uris {
+		// If the change is only on-disk and the file is not open, don't
+		// directly request its package. It may not be a workspace package.
+		if onDisk && !snapshot.IsOpen(uri) {
+			continue
+		}
 		pkgs, err := snapshot.PackagesForFile(ctx, uri, source.TypecheckWorkspace)
 		if err != nil {
 			// TODO (rFindley): we should probably do something with the error here,
diff --git a/internal/lsp/text_synchronization.go b/internal/lsp/text_synchronization.go
index 205331dfac..fc35ff5d58 100644
--- a/internal/lsp/text_synchronization.go
+++ b/internal/lsp/text_synchronization.go
@@ -236,7 +236,7 @@ func (s *Server) didModifyFiles(ctx context.Context, modifications []source.File
 		diagnosticWG.Add(1)
 		go func(snapshot source.Snapshot, uris []span.URI) {
 			defer diagnosticWG.Done()
-			s.diagnoseSnapshot(snapshot, uris)
+			s.diagnoseSnapshot(snapshot, uris, cause == FromDidChangeWatchedFiles)
 		}(snapshot, uris)
 	}