diff --git a/.changeset/some-parts-watch.md b/.changeset/some-parts-watch.md
new file mode 100644
index 0000000000..7d19a32f22
--- /dev/null
+++ b/.changeset/some-parts-watch.md
@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: type BigInts in `$state.snapshot(...)` return values
diff --git a/packages/svelte/src/ambient.d.ts b/packages/svelte/src/ambient.d.ts
index bbbc86c997..ed0a004fa1 100644
--- a/packages/svelte/src/ambient.d.ts
+++ b/packages/svelte/src/ambient.d.ts
@@ -24,7 +24,7 @@ declare function $state<T>(initial: T): T;
 declare function $state<T>(): T | undefined;
 
 declare namespace $state {
-	type Primitive = string | number | boolean | null | undefined;
+	type Primitive = string | number | bigint | boolean | null | undefined;
 
 	type TypedArray =
 		| Int8Array
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index 1c3795be80..5f41fabf60 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -3229,7 +3229,7 @@ declare function $state<T>(initial: T): T;
 declare function $state<T>(): T | undefined;
 
 declare namespace $state {
-	type Primitive = string | number | boolean | null | undefined;
+	type Primitive = string | number | bigint | boolean | null | undefined;
 
 	type TypedArray =
 		| Int8Array