diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index f36d7d8901..f4ea3370d8 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -825,6 +825,8 @@ export function flushSync(fn) {
 	if (fn) {
 		is_flushing = true;
 		flush_queued_root_effects();
+
+		is_flushing = true;
 		result = fn();
 	}