diff --git a/internal/lsp/protocol/span.go b/internal/lsp/protocol/span.go
index f41fba82..36ea0b55 100644
--- a/internal/lsp/protocol/span.go
+++ b/internal/lsp/protocol/span.go
@@ -23,14 +23,13 @@ func NewURI(uri span.URI) string {
 	return string(uri)
 }
 
-func NewColumnMapper(uri span.URI, fn string, fset *token.FileSet, f *token.File, content []byte) *ColumnMapper {
+func NewColumnMapper(uri span.URI, filename string, fset *token.FileSet, f *token.File, content []byte) *ColumnMapper {
 	var converter *span.TokenConverter
 	if f == nil {
-		converter = span.NewContentConverter(fn, content)
+		converter = span.NewContentConverter(filename, content)
 	} else {
 		converter = span.NewTokenConverter(fset, f)
 	}
-
 	return &ColumnMapper{
 		URI:       uri,
 		Converter: converter,
diff --git a/internal/lsp/source/diagnostics.go b/internal/lsp/source/diagnostics.go
index 29779284..f66e2786 100644
--- a/internal/lsp/source/diagnostics.go
+++ b/internal/lsp/source/diagnostics.go
@@ -88,10 +88,6 @@ func Diagnostics(ctx context.Context, v View, uri span.URI) (map[span.URI][]Diag
 	}
 	// Updates to the diagnostics for this package may need to be propagated.
 	for _, f := range gof.GetActiveReverseDeps(ctx) {
-		if f == nil {
-			v.Session().Logger().Errorf(ctx, "nil file in reverse active dependencies for %s", f.URI())
-			continue
-		}
 		pkg := f.GetPackage(ctx)
 		if pkg == nil {
 			continue
diff --git a/internal/lsp/text_synchronization.go b/internal/lsp/text_synchronization.go
index d8c219e7..20a0ffa9 100644
--- a/internal/lsp/text_synchronization.go
+++ b/internal/lsp/text_synchronization.go
@@ -65,11 +65,16 @@ func (s *Server) applyChanges(ctx context.Context, params *protocol.DidChangeTex
 
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)
-	file, m, err := getSourceFile(ctx, view, uri)
+	f, m, err := getSourceFile(ctx, view, uri)
 	if err != nil {
 		return "", jsonrpc2.NewErrorf(jsonrpc2.CodeInternalError, "file not found")
 	}
-	content := file.GetContent(ctx)
+	fset := f.GetFileSet(ctx)
+	filename, err := f.URI().Filename()
+	if err != nil {
+		return "", jsonrpc2.NewErrorf(jsonrpc2.CodeInternalError, "no filename for %s", uri)
+	}
+	content := f.GetContent(ctx)
 	for _, change := range params.ContentChanges {
 		spn, err := m.RangeSpan(*change.Range)
 		if err != nil {
@@ -87,6 +92,9 @@ func (s *Server) applyChanges(ctx context.Context, params *protocol.DidChangeTex
 		buf.WriteString(change.Text)
 		buf.Write(content[end:])
 		content = buf.Bytes()
+
+		// Update column mapper along with the content.
+		m = protocol.NewColumnMapper(f.URI(), filename, fset, nil, content)
 	}
 	return string(content), nil
 }
diff --git a/internal/lsp/util.go b/internal/lsp/util.go
index aa8be476..a41ba565 100644
--- a/internal/lsp/util.go
+++ b/internal/lsp/util.go
@@ -51,13 +51,11 @@ func getSourceFile(ctx context.Context, v source.View, uri span.URI) (source.Fil
 	if err != nil {
 		return nil, nil, err
 	}
-
-	fname, err := f.URI().Filename()
+	filename, err := f.URI().Filename()
 	if err != nil {
 		return nil, nil, err
 	}
-
-	m := protocol.NewColumnMapper(f.URI(), fname, f.GetFileSet(ctx), f.GetToken(ctx), f.GetContent(ctx))
+	m := protocol.NewColumnMapper(f.URI(), filename, f.GetFileSet(ctx), f.GetToken(ctx), f.GetContent(ctx))
 
 	return f, m, nil
 }