diff --git a/.changeset/fluffy-colts-grin.md b/.changeset/fluffy-colts-grin.md
new file mode 100644
index 0000000000..f4023f454d
--- /dev/null
+++ b/.changeset/fluffy-colts-grin.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+feat: move dev-time component properties to private symbols'
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index e0e55c5337..0ef05eeac0 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -418,7 +418,7 @@ export function client_component(source, analysis, options) {
 
 	if (options.hmr) {
 		const accept_fn_body = [
-			b.stmt(b.call('$.set', b.id('s'), b.member(b.id('module.default'), b.id('original'))))
+			b.stmt(b.call('$.set', b.id('s'), b.member(b.id('module.default'), b.id('$.ORIGINAL'), true)))
 		];
 
 		if (analysis.css.hash) {
@@ -446,7 +446,11 @@ export function client_component(source, analysis, options) {
 			// Assign the original component to the wrapper so we can use it on hot reload patching,
 			// else we would call the HMR function two times
 			b.stmt(
-				b.assignment('=', b.member(b.id(analysis.name), b.id('original')), b.id('$$original'))
+				b.assignment(
+					'=',
+					b.member(b.id(analysis.name), b.id('$.ORIGINAL'), true),
+					b.id('$$original')
+				)
 			),
 			b.stmt(b.call('import.meta.hot.accept', b.arrow([b.id('module')], b.block(accept_fn_body))))
 		]);
@@ -458,10 +462,14 @@ export function client_component(source, analysis, options) {
 
 	if (options.dev) {
 		if (filename) {
-			// add `App.filename = 'App.svelte'` so that we can print useful messages later
+			// add `App[$.FILENAME] = 'App.svelte'` so that we can print useful messages later
 			body.unshift(
 				b.stmt(
-					b.assignment('=', b.member(b.id(analysis.name), b.id('filename')), b.literal(filename))
+					b.assignment(
+						'=',
+						b.member(b.id(analysis.name), b.id('$.FILENAME'), true),
+						b.literal(filename)
+					)
 				)
 			);
 		}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
index d005b23c5d..573efe211a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
@@ -1640,7 +1640,7 @@ export const template_visitors = {
 				call = b.call(
 					'$.add_locations',
 					call,
-					b.member(b.id(context.state.analysis.name), b.id('filename')),
+					b.member(b.id(context.state.analysis.name), b.id('$.FILENAME'), true),
 					serialize_locations(state.locations)
 				);
 			}
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js b/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
index 4519b06ead..3038316ede 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
@@ -2249,10 +2249,14 @@ export function server_component(analysis, options) {
 	}
 
 	if (options.dev && filename) {
-		// add `App.filename = 'App.svelte'` so that we can print useful messages later
+		// add `App[$.FILENAME] = 'App.svelte'` so that we can print useful messages later
 		body.unshift(
 			b.stmt(
-				b.assignment('=', b.member(b.id(analysis.name), b.id('filename')), b.literal(filename))
+				b.assignment(
+					'=',
+					b.member(b.id(analysis.name), b.id('$.FILENAME'), true),
+					b.literal(filename)
+				)
 			)
 		);
 	}
diff --git a/packages/svelte/src/constants.js b/packages/svelte/src/constants.js
index 6f5b03ec38..f6adc94f50 100644
--- a/packages/svelte/src/constants.js
+++ b/packages/svelte/src/constants.js
@@ -30,6 +30,10 @@ export const ELEMENT_PRESERVE_ATTRIBUTE_CASE = 1 << 1;
 
 export const UNINITIALIZED = Symbol();
 
+// Dev-time component properties
+export const FILENAME = Symbol('filename');
+export const ORIGINAL = Symbol('original');
+
 /** List of elements that require raw contents and should not have SSR comments put in them */
 export const RawTextElements = ['textarea', 'script', 'style', 'title'];
 
diff --git a/packages/svelte/src/internal/client/dev/legacy.js b/packages/svelte/src/internal/client/dev/legacy.js
index 1262c62db0..25473f54c4 100644
--- a/packages/svelte/src/internal/client/dev/legacy.js
+++ b/packages/svelte/src/internal/client/dev/legacy.js
@@ -1,11 +1,12 @@
 import * as e from '../errors.js';
 import { current_component_context } from '../runtime.js';
+import { FILENAME } from '../../../constants.js';
 import { get_component } from './ownership.js';
 
-/** @param {Function & { filename: string }} target */
+/** @param {Function & { [FILENAME]: string }} target */
 export function check_target(target) {
 	if (target) {
-		e.component_api_invalid_new(target.filename ?? 'a component', target.name);
+		e.component_api_invalid_new(target[FILENAME] ?? 'a component', target.name);
 	}
 }
 
@@ -15,8 +16,8 @@ export function legacy_api() {
 	/** @param {string} method */
 	function error(method) {
 		// @ts-expect-error
-		const parent = get_component()?.filename ?? 'Something';
-		e.component_api_changed(parent, method, component.filename);
+		const parent = get_component()?.[FILENAME] ?? 'Something';
+		e.component_api_changed(parent, method, component[FILENAME]);
 	}
 
 	return {
diff --git a/packages/svelte/src/internal/client/dev/ownership.js b/packages/svelte/src/internal/client/dev/ownership.js
index 4f07a57554..7d10118788 100644
--- a/packages/svelte/src/internal/client/dev/ownership.js
+++ b/packages/svelte/src/internal/client/dev/ownership.js
@@ -6,6 +6,7 @@ import { render_effect, user_pre_effect } from '../reactivity/effects.js';
 import { dev_current_component_function } from '../runtime.js';
 import { get_prototype_of } from '../../shared/utils.js';
 import * as w from '../warnings.js';
+import { FILENAME } from '../../../constants.js';
 
 /** @type {Record<string, Array<{ start: Location, end: Location, component: Function }>>} */
 const boundaries = {};
@@ -115,8 +116,8 @@ export function add_owner(object, owner, global = false) {
 		if (metadata && !has_owner(metadata, component)) {
 			let original = get_owner(metadata);
 
-			if (owner.filename !== component.filename) {
-				w.ownership_invalid_binding(component.filename, owner.filename, original.filename);
+			if (owner[FILENAME] !== component[FILENAME]) {
+				w.ownership_invalid_binding(component[FILENAME], owner[FILENAME], original[FILENAME]);
 			}
 		}
 	}
@@ -236,9 +237,9 @@ export function check_ownership(metadata) {
 		let original = get_owner(metadata);
 
 		// @ts-expect-error
-		if (original.filename !== component.filename) {
+		if (original[FILENAME] !== component[FILENAME]) {
 			// @ts-expect-error
-			w.ownership_invalid_mutation(component.filename, original.filename);
+			w.ownership_invalid_mutation(component[FILENAME], original[FILENAME]);
 		} else {
 			w.ownership_invalid_mutation();
 		}
diff --git a/packages/svelte/src/internal/client/dom/blocks/html.js b/packages/svelte/src/internal/client/dom/blocks/html.js
index 055d94a77a..3c4051261e 100644
--- a/packages/svelte/src/internal/client/dom/blocks/html.js
+++ b/packages/svelte/src/internal/client/dom/blocks/html.js
@@ -1,5 +1,5 @@
 /** @import { Effect, TemplateNode } from '#client' */
-import { HYDRATION_ERROR } from '../../../../constants.js';
+import { FILENAME, HYDRATION_ERROR } from '../../../../constants.js';
 import { block, branch, destroy_effect } from '../../reactivity/effects.js';
 import { hydrate_next, hydrate_node, hydrating, set_hydrate_node } from '../hydration.js';
 import { create_fragment_from_html } from '../reconciler.js';
@@ -23,8 +23,8 @@ function check_hash(element, server_hash, value) {
 	const loc = element.__svelte_meta?.loc;
 	if (loc) {
 		location = `near ${loc.file}:${loc.line}:${loc.column}`;
-	} else if (dev_current_component_function?.filename) {
-		location = `in ${dev_current_component_function.filename}`;
+	} else if (dev_current_component_function?.[FILENAME]) {
+		location = `in ${dev_current_component_function[FILENAME]}`;
 	}
 
 	w.hydration_html_changed(
diff --git a/packages/svelte/src/internal/client/dom/blocks/svelte-element.js b/packages/svelte/src/internal/client/dom/blocks/svelte-element.js
index 1df6c8acab..e6886bb7fa 100644
--- a/packages/svelte/src/internal/client/dom/blocks/svelte-element.js
+++ b/packages/svelte/src/internal/client/dom/blocks/svelte-element.js
@@ -1,5 +1,5 @@
 /** @import { Effect, EffectNodes, TemplateNode } from '#client' */
-import { namespace_svg } from '../../../../constants.js';
+import { FILENAME, namespace_svg } from '../../../../constants.js';
 import {
 	hydrate_next,
 	hydrate_node,
@@ -38,7 +38,7 @@ export function element(node, get_tag, is_svg, render_fn, get_namespace, locatio
 		hydrate_next();
 	}
 
-	var filename = DEV && location && current_component_context?.function.filename;
+	var filename = DEV && location && current_component_context?.function[FILENAME];
 
 	/** @type {string | null} */
 	var tag;
diff --git a/packages/svelte/src/internal/client/index.js b/packages/svelte/src/internal/client/index.js
index e42efdcd11..60dd1d0aa2 100644
--- a/packages/svelte/src/internal/client/index.js
+++ b/packages/svelte/src/internal/client/index.js
@@ -1,3 +1,4 @@
+export { FILENAME, ORIGINAL } from '../../constants.js';
 export { add_locations } from './dev/elements.js';
 export { hmr } from './dev/hmr.js';
 export {
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 78e0a7c8e0..922193f10e 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -29,6 +29,7 @@ import { mutate, set, source } from './reactivity/sources.js';
 import { update_derived } from './reactivity/deriveds.js';
 import * as e from './errors.js';
 import { lifecycle_outside_component } from '../shared/errors.js';
+import { FILENAME } from '../../constants.js';
 
 const FLUSH_MICROTASK = 0;
 const FLUSH_SYNC = 1;
@@ -226,7 +227,7 @@ function handle_error(error, effect, component_context) {
 
 	while (current_context !== null) {
 		/** @type {string} */
-		var filename = current_context.function?.filename;
+		var filename = current_context.function?.[FILENAME];
 
 		if (filename) {
 			const file = filename.split('/').pop();
diff --git a/packages/svelte/src/internal/client/validate.js b/packages/svelte/src/internal/client/validate.js
index 036936f9a8..5c6f6a6553 100644
--- a/packages/svelte/src/internal/client/validate.js
+++ b/packages/svelte/src/internal/client/validate.js
@@ -1,6 +1,7 @@
 import { untrack } from './runtime.js';
 import { get_descriptor, is_array } from '../shared/utils.js';
 import * as e from './errors.js';
+import { FILENAME } from '../../constants.js';
 
 /** regex of all html void element names */
 const void_element_names =
@@ -70,7 +71,7 @@ export function validate_each_keys(collection, key_fn) {
  * @param {Record<string, any>} $$props
  * @param {string[]} bindable
  * @param {string[]} exports
- * @param {Function & { filename: string }} component
+ * @param {Function & { [FILENAME]: string }} component
  */
 export function validate_prop_bindings($$props, bindable, exports, component) {
 	for (const key in $$props) {
@@ -79,11 +80,11 @@ export function validate_prop_bindings($$props, bindable, exports, component) {
 
 		if (setter) {
 			if (exports.includes(key)) {
-				e.bind_invalid_export(component.filename, key, name);
+				e.bind_invalid_export(component[FILENAME], key, name);
 			}
 
 			if (!bindable.includes(key)) {
-				e.bind_not_bindable(key, component.filename, name);
+				e.bind_not_bindable(key, component[FILENAME], name);
 			}
 		}
 	}
diff --git a/packages/svelte/src/internal/server/dev.js b/packages/svelte/src/internal/server/dev.js
index 870f9aa9d0..045dda5948 100644
--- a/packages/svelte/src/internal/server/dev.js
+++ b/packages/svelte/src/internal/server/dev.js
@@ -1,4 +1,5 @@
 import {
+	FILENAME,
 	disallowed_paragraph_contents,
 	interactive_elements,
 	is_tag_valid_with_parent
@@ -56,7 +57,7 @@ function print_error(payload, parent, child) {
  * @param {number} column
  */
 export function push_element(payload, tag, line, column) {
-	var filename = /** @type {import('#server').Component} */ (current_component).function.filename;
+	var filename = /** @type {import('#server').Component} */ (current_component).function[FILENAME];
 	var child = { tag, parent, filename, line, column };
 
 	if (parent !== null && !is_tag_valid_with_parent(tag, parent.tag)) {
diff --git a/packages/svelte/src/internal/server/index.js b/packages/svelte/src/internal/server/index.js
index 2cb741ad95..a1a2d3febc 100644
--- a/packages/svelte/src/internal/server/index.js
+++ b/packages/svelte/src/internal/server/index.js
@@ -1,5 +1,6 @@
 /** @import { Component, Payload, RenderOutput } from '#server' */
 /** @import { Store } from '#shared' */
+export { FILENAME, ORIGINAL } from '../../constants.js';
 import { is_promise, noop } from '../shared/utils.js';
 import { subscribe_to_store } from '../../store/utils.js';
 import {
diff --git a/packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js
index 9037c5dd25..44600907c1 100644
--- a/packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js
@@ -16,10 +16,10 @@ if (import.meta.hot) {
 
 	Hmr = $.hmr(s);
 	Hmr.filename = filename;
-	Hmr.original = $$original;
+	Hmr[$.ORIGINAL] = $$original;
 
 	import.meta.hot.accept((module) => {
-		$.set(s, module.default.original);
+		$.set(s, module.default[$.ORIGINAL]);
 	});
 }