diff --git a/.changeset/wise-radios-exercise.md b/.changeset/wise-radios-exercise.md
new file mode 100644
index 0000000000..1d13af7758
--- /dev/null
+++ b/.changeset/wise-radios-exercise.md
@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: improve unstate handling of non enumerable properties
diff --git a/packages/svelte/src/internal/client/proxy.js b/packages/svelte/src/internal/client/proxy.js
index 23440a56e4..8add490a10 100644
--- a/packages/svelte/src/internal/client/proxy.js
+++ b/packages/svelte/src/internal/client/proxy.js
@@ -84,10 +84,11 @@ function unwrap(value, already_unwrapped = new Map()) {
 		} else {
 			/** @type {Record<string | symbol, any>} */
 			const obj = {};
-			const keys = object_keys(value);
+			const keys = Reflect.ownKeys(value);
 			const descriptors = get_descriptors(value);
 			already_unwrapped.set(value, obj);
 			for (const key of keys) {
+				if (key === STATE_SYMBOL || (DEV && key === READONLY_SYMBOL)) continue;
 				if (descriptors[key].get) {
 					define_property(obj, key, descriptors[key]);
 				} else {