diff --git a/.changeset/mean-taxis-yell.md b/.changeset/mean-taxis-yell.md
new file mode 100644
index 0000000000..6257720d08
--- /dev/null
+++ b/.changeset/mean-taxis-yell.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: narrow `defaultChecked` to boolean
diff --git a/packages/svelte/elements.d.ts b/packages/svelte/elements.d.ts
index 71f28b4f97..0172b0e358 100644
--- a/packages/svelte/elements.d.ts
+++ b/packages/svelte/elements.d.ts
@@ -1115,8 +1115,8 @@ export interface HTMLInputAttributes extends HTMLAttributes<HTMLInputElement> {
 	// needs both casing variants because language tools does lowercase names of non-shorthand attributes
 	defaultValue?: any;
 	defaultvalue?: any;
-	defaultChecked?: any;
-	defaultchecked?: any;
+	defaultChecked?: boolean | undefined | null;
+	defaultchecked?: boolean | undefined | null;
 	width?: number | string | undefined | null;
 	webkitdirectory?: boolean | undefined | null;