diff --git a/.changeset/wet-games-fly.md b/.changeset/wet-games-fly.md
new file mode 100644
index 0000000000..9f03e26882
--- /dev/null
+++ b/.changeset/wet-games-fly.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: type-level back-compat for default slot and children prop
diff --git a/packages/svelte/src/main/public.d.ts b/packages/svelte/src/main/public.d.ts
index 63f5122bbe..5849835ea2 100644
--- a/packages/svelte/src/main/public.d.ts
+++ b/packages/svelte/src/main/public.d.ts
@@ -18,6 +18,14 @@ export interface ComponentConstructorOptions<
 	$$inline?: boolean;
 }
 
+// Utility type for ensuring backwards compatibility on a type level: If there's a default slot, add 'children' to the props if it doesn't exist there already
+type PropsWithChildren<Props, Slots> = Props &
+	(Props extends { children?: any }
+		? {}
+		: Slots extends { default: any }
+		? { children?: Snippet }
+		: {});
+
 /**
  * Can be used to create strongly typed Svelte components.
  *
@@ -57,13 +65,13 @@ export class SvelteComponent<
 	 * is a stop-gap solution. Migrate towards using `mount` or `createRoot` instead. See
 	 * https://svelte-5-preview.vercel.app/docs/breaking-changes#components-are-no-longer-classes for more info.
 	 */
-	constructor(options: ComponentConstructorOptions<Props>);
+	constructor(options: ComponentConstructorOptions<PropsWithChildren<Props, Slots>>);
 	/**
 	 * For type checking capabilities only.
 	 * Does not exist at runtime.
 	 * ### DO NOT USE!
 	 * */
-	$$prop_def: Props;
+	$$prop_def: PropsWithChildren<Props, Slots>;
 	/**
 	 * For type checking capabilities only.
 	 * Does not exist at runtime.
diff --git a/packages/svelte/tests/types/component.ts b/packages/svelte/tests/types/component.ts
index 749c648e2f..13ebb65753 100644
--- a/packages/svelte/tests/types/component.ts
+++ b/packages/svelte/tests/types/component.ts
@@ -15,11 +15,11 @@ class LegacyComponent extends SvelteComponent<
 	{ slot: { slotProps: boolean } }
 > {}
 
-// @ts-expect-error
 const legacyComponent = new LegacyComponent({
 	target: null as any as Document | Element | ShadowRoot,
 	props: {
 		prop: 'foo',
+		// @ts-expect-error
 		x: ''
 	}
 });
@@ -56,14 +56,20 @@ class NewComponent extends SvelteComponent<
 	anExport: string = '';
 }
 
-// @ts-expect-error
 new NewComponent({
-	prop: 'foo',
-	x: ''
+	target: null as any,
+	props: {
+		prop: 'foo',
+		// @ts-expect-error
+		x: ''
+	}
 });
 
 const newComponent: NewComponent = new NewComponent({
-	prop: 'foo'
+	target: null as any,
+	props: {
+		prop: 'foo'
+	}
 });
 newComponent.$$events_def.event;
 // @ts-expect-error
@@ -123,11 +129,11 @@ instance.anExport === 1;
 // --------------------------------------------------------------------------- interop
 
 const AsLegacyComponent = asClassComponent(newComponent);
-// @ts-expect-error
 new AsLegacyComponent({
 	target: null as any,
 	props: {
 		prop: '',
+		// @ts-expect-error
 		x: ''
 	}
 });