diff --git a/src/runtime/server/astro-island.ts b/src/runtime/server/astro-island.ts
index 4f743263110b..d3a22a5c2d09 100644
--- a/src/runtime/server/astro-island.ts
+++ b/src/runtime/server/astro-island.ts
@@ -42,7 +42,7 @@ declare const Astro: {
 				public hydrator: any;
 				static observedAttributes = ['props'];
 				connectedCallback() {
-					if (this.getAttribute('client') === 'only' || this.firstChild) {
+					if (!this.getAttribute('await-children') || this.firstChild) {
 						this.childrenConnectedCallback();
 					} else {
 						// connectedCallback may run *before* children are rendered (ex. HTML streaming)
diff --git a/src/runtime/server/index.ts b/src/runtime/server/index.ts
index 230c043edb3e..8188e716520b 100644
--- a/src/runtime/server/index.ts
+++ b/src/runtime/server/index.ts
@@ -452,6 +452,10 @@ If you're still stuck, please open an issue on GitHub or join us at https://astr
 
 	island.children = `${html ?? ''}${template}`;
 
+	if (island.children) {
+		island.props['await-children'] = ''
+	}
+
 	// Scripts to prepend
 	let prescriptType: PrescriptType = needsHydrationScript
 		? 'both'