diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index 942df44e5a..a86ccfee4f 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -140,7 +140,7 @@ export function set(source, value, should_proxy = false) {
 		(!untracking || (active_reaction.f & INSPECT_EFFECT) !== 0) &&
 		is_runes() &&
 		(active_reaction.f & (DERIVED | BLOCK_EFFECT | INSPECT_EFFECT)) !== 0 &&
-		!(source_ownership?.sources.includes(source) && source_ownership.reaction === active_reaction)
+		!(source_ownership?.reaction === active_reaction && source_ownership.sources.includes(source))
 	) {
 		e.state_unsafe_mutation();
 	}
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 0bb357fbbc..fce6c78b56 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -235,8 +235,12 @@ function schedule_possible_effect_self_invalidation(signal, effect, root = true)
 	for (var i = 0; i < reactions.length; i++) {
 		var reaction = reactions[i];
 
-		if (source_ownership?.sources.includes(signal) && source_ownership.reaction === active_reaction)
+		if (
+			source_ownership?.reaction === active_reaction &&
+			source_ownership.sources.includes(signal)
+		) {
 			continue;
+		}
 
 		if ((reaction.f & DERIVED) !== 0) {
 			schedule_possible_effect_self_invalidation(/** @type {Derived} */ (reaction), effect, false);
@@ -741,8 +745,8 @@ export function get(signal) {
 	// Register the dependency on the current reaction signal.
 	if (active_reaction !== null && !untracking) {
 		if (
-			!source_ownership?.sources.includes(signal) ||
-			source_ownership.reaction !== active_reaction
+			source_ownership?.reaction !== active_reaction ||
+			!source_ownership?.sources.includes(signal)
 		) {
 			var deps = active_reaction.deps;
 			if (signal.rv < read_version) {