diff --git a/src/editorExtension/syntaxHighlight.ts b/src/editorExtension/syntaxHighlight.ts
index e935110..36b885f 100644
--- a/src/editorExtension/syntaxHighlight.ts
+++ b/src/editorExtension/syntaxHighlight.ts
@@ -50,7 +50,7 @@ export class SQLSealViewPlugin implements PluginValue {
 
   destroy(): void { }
 
-  private parseWithGrammar(sql: string) {
+  private parseWithGrammar(sql: string): Decorator[] {
     const grammar = ohm.grammar(SQLSealLangDefinition(this.renderers.getViewDefinitions(), this.renderers.flags, true));
 
     // FIXME: extend grammar with error line.