diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index c35b0a84e0..44eb2b1ad8 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -8,7 +8,6 @@ import {
 	current_untracking,
 	flushSync,
 	get,
-	ignore_mutation_validation,
 	is_batching_effect,
 	is_runes,
 	mark_reactions,
@@ -19,7 +18,7 @@ import {
 	untrack
 } from '../runtime.js';
 import { equals, safe_equals } from './equality.js';
-import { CLEAN, DERIVED, DIRTY, MANAGED } from '../constants.js';
+import { CLEAN, DERIVED, DIRTY, MANAGED, UNINITIALIZED } from '../constants.js';
 
 /**
  * @template V
@@ -93,9 +92,11 @@ export function mutate(source, value) {
  * @returns {V}
  */
 export function set(signal, value) {
+	var initialized = signal.v !== UNINITIALIZED;
+
 	if (
 		!current_untracking &&
-		!ignore_mutation_validation &&
+		initialized &&
 		current_reaction !== null &&
 		is_runes() &&
 		(current_reaction.f & DERIVED) !== 0
@@ -124,11 +125,10 @@ export function set(signal, value) {
 		//
 		// $effect(() => x++)
 		//
-		// We additionally want to skip this logic for when ignore_mutation_validation is
-		// true, as stores write to source signal on initialisation.
+		// We additionally want to skip this logic when initialising store sources
 		if (
 			is_runes() &&
-			!ignore_mutation_validation &&
+			initialized &&
 			current_effect !== null &&
 			(current_effect.f & CLEAN) !== 0 &&
 			(current_effect.f & MANAGED) === 0
diff --git a/packages/svelte/src/internal/client/reactivity/store.js b/packages/svelte/src/internal/client/reactivity/store.js
index 7ea57428da..1d07f59288 100644
--- a/packages/svelte/src/internal/client/reactivity/store.js
+++ b/packages/svelte/src/internal/client/reactivity/store.js
@@ -1,7 +1,7 @@
 import { subscribe_to_store } from '../../../store/utils.js';
 import { noop } from '../../common.js';
 import { UNINITIALIZED } from '../constants.js';
-import { get, set_ignore_mutation_validation, untrack } from '../runtime.js';
+import { get, untrack } from '../runtime.js';
 import { user_effect } from './effects.js';
 import { mutable_source, set } from './sources.js';
 
@@ -74,13 +74,7 @@ function connect_store_to_signal(store, source) {
 		return noop;
 	}
 
-	/** @param {V} v */
-	const run = (v) => {
-		set_ignore_mutation_validation(true);
-		set(source, v);
-		set_ignore_mutation_validation(false);
-	};
-	return subscribe_to_store(store, run);
+	return subscribe_to_store(store, (v) => set(source, v));
 }
 
 /**
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 4c45dd0f22..2620cddddd 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -84,12 +84,6 @@ export function set_last_inspected_signal(signal) {
 
 /** If `true`, `get`ting the signal should not register it as a dependency */
 export let current_untracking = false;
-/** Exists to opt out of the mutation validation for stores which may be set for the first time during a derivation */
-export let ignore_mutation_validation = false;
-/** @param {boolean} value */
-export function set_ignore_mutation_validation(value) {
-	ignore_mutation_validation = value;
-}
 
 // If we are working with a get() chain that has no active container,
 // to prevent memory leaks, we skip adding the reaction.