diff --git a/packages/html2/src/index.ts b/packages/html2/src/index.ts
index 9401169..9633941 100644
--- a/packages/html2/src/index.ts
+++ b/packages/html2/src/index.ts
@@ -39,7 +39,14 @@ export class Widget implements EventTarget {
 
         dataflow {
             const oldNode = this.node.value;
-            const newNode = template`${this.nodeGenerator(template)}`.node();
+
+            const fragments = template`${this.nodeGenerator(template)}`;
+            const newNodes = fragments.nodes();
+            if (newNodes.length > 1) {
+                throw new Error(`@syndicate-lang/html2: Multiple nodes returned from template: ${fragments.toString()}`);
+            }
+            const newNode = newNodes[0];
+
             if (oldNode !== newNode) {
                 if (oldNode !== null) {
                     for (const [type, cbs] of this.callbacks.entries()) {