diff --git a/packages/core/src/util/assert.ts b/packages/core/src/util/assert.ts
index 1f1aeedf8e..ea9ed55542 100644
--- a/packages/core/src/util/assert.ts
+++ b/packages/core/src/util/assert.ts
@@ -65,8 +65,9 @@ export function throwError(msg: string): never {
 }
 
 export function assertDomNode(node: any) {
+  // If we're in a worker, `Node` will not be defined.
   assertEqual(
-      node instanceof Node ||
+      (typeof Node !== 'undefined' && node instanceof Node) ||
           (typeof node === 'object' && node.constructor.name === 'WebWorkerRenderNode'),
       true, 'The provided value must be an instance of a DOM Node');
 }