diff --git a/frontend/src/metabase/query_builder/components/expressions/ExpressionEditorTextfield.jsx b/frontend/src/metabase/query_builder/components/expressions/ExpressionEditorTextfield.jsx
index 0833d0f001bee8b45116d112dfbb81e152afe525..fe33f7750566a69e8feb9873c7b036baac2e7ffc 100644
--- a/frontend/src/metabase/query_builder/components/expressions/ExpressionEditorTextfield.jsx
+++ b/frontend/src/metabase/query_builder/components/expressions/ExpressionEditorTextfield.jsx
@@ -406,6 +406,7 @@ export default class ExpressionEditorTextfield extends React.Component {
           <EditorEqualsSign>=</EditorEqualsSign>
           <AceEditor
             commands={this.commands}
+            mode="text"
             ref={this.input}
             value={source}
             markers={this.errorAsMarkers(errorMessage)}