diff --git a/packages/svelte/src/attachments/public.d.ts b/packages/svelte/src/attachments/public.d.ts
index bda77a8e7d..8680139bc7 100644
--- a/packages/svelte/src/attachments/public.d.ts
+++ b/packages/svelte/src/attachments/public.d.ts
@@ -15,7 +15,7 @@ export interface FromAction<Element extends EventTarget = HTMLElement, Par = unk
 	<Node extends Element, Parameter extends Par>(
 		...args: undefined extends NoInfer<Parameter>
 			? [
-					action: (node: Node, parameter?: Parameter) => void | ActionReturn<Parameter>,
+					action: (node: Node, parameter?: never) => void | ActionReturn<Parameter>,
 					parameter?: () => NoInfer<Parameter>
 				]
 			: [
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index 1c96afd61f..0822c02d6d 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -641,7 +641,7 @@ declare module 'svelte/attachments' {
 		<Node extends Element, Parameter extends Par>(
 			...args: undefined extends NoInfer<Parameter>
 				? [
-						action: (node: Node, parameter?: Parameter) => void | ActionReturn<Parameter>,
+						action: (node: Node, parameter?: never) => void | ActionReturn<Parameter>,
 						parameter?: () => NoInfer<Parameter>
 					]
 				: [
@@ -673,7 +673,7 @@ declare module 'svelte/attachments' {
 	 * @since 5.29
 	 */
 	export function createAttachmentKey(): symbol;
-	export function fromAction<Node extends HTMLElement, Parameter extends any>(...args: undefined extends NoInfer<Parameter> ? [action: (node: Node, parameter?: Parameter | undefined) => void | ActionReturn<Parameter, Record<never, any>>, parameter?: (() => NoInfer<Parameter>) | undefined] : [action: (node: Node, parameter: Parameter) => void | ActionReturn<Parameter, Record<never, any>>, parameter: () => NoInfer<Parameter>]): Attachment<Node>;
+	export function fromAction<Node extends HTMLElement, Parameter extends any>(...args: undefined extends NoInfer<Parameter> ? [action: (node: Node, parameter?: never) => void | ActionReturn<Parameter, Record<never, any>>, parameter?: (() => NoInfer<Parameter>) | undefined] : [action: (node: Node, parameter: Parameter) => void | ActionReturn<Parameter, Record<never, any>>, parameter: () => NoInfer<Parameter>]): Attachment<Node>;
 
 	export {};
 }