diff --git a/core/block_svg.ts b/core/block_svg.ts
index bc02ef63810..1e4fc095570 100644
--- a/core/block_svg.ts
+++ b/core/block_svg.ts
@@ -524,9 +524,12 @@ export class BlockSvg
     if (!collapsed) {
       this.updateDisabled();
       this.removeInput(collapsedInputName);
+      dom.removeClass(this.svgGroup_, 'blocklyCollapsed');
       return;
     }
 
+    dom.addClass(this.svgGroup_, 'blocklyCollapsed');
+
     const text = this.toString(internalConstants.COLLAPSE_CHARS);
     const field = this.getField(collapsedFieldName);
     if (field) {