diff --git a/.changeset/quiet-crabs-nail.md b/.changeset/quiet-crabs-nail.md
new file mode 100644
index 0000000000..78ea5ba14e
--- /dev/null
+++ b/.changeset/quiet-crabs-nail.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: take into account member expressions when determining legacy reactive dependencies
diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index dc98fb31e6..781ccdfc60 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/index.js
@@ -500,7 +500,15 @@ const legacy_scope_tweaker = {
 			node.body.type === 'ExpressionStatement' &&
 			node.body.expression.type === 'AssignmentExpression'
 		) {
-			for (const id of extract_identifiers(node.body.expression.left)) {
+			let ids = extract_identifiers(node.body.expression.left);
+			if (node.body.expression.left.type === 'MemberExpression') {
+				const id = object(node.body.expression.left);
+				if (id !== null) {
+					ids = [id];
+				}
+			}
+
+			for (const id of ids) {
 				const binding = state.scope.get(id.name);
 				if (binding?.kind === 'legacy_reactive') {
 					// TODO does this include `let double; $: double = x * 2`?
@@ -511,8 +519,15 @@ const legacy_scope_tweaker = {
 	},
 	AssignmentExpression(node, { state, next }) {
 		if (state.reactive_statement && node.operator === '=') {
-			for (const id of extract_identifiers(node.left)) {
-				state.reactive_statement.assignments.add(id);
+			if (node.left.type === 'MemberExpression') {
+				const id = object(node.left);
+				if (id !== null) {
+					state.reactive_statement.assignments.add(id);
+				}
+			} else {
+				for (const id of extract_identifiers(node.left)) {
+					state.reactive_statement.assignments.add(id);
+				}
 			}
 		}
 
diff --git a/packages/svelte/tests/runtime-legacy/samples/reactive-value-assign-properties/_config.js b/packages/svelte/tests/runtime-legacy/samples/reactive-value-assign-properties/_config.js
new file mode 100644
index 0000000000..9c66e2e6db
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/reactive-value-assign-properties/_config.js
@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+	html: `1 1`
+});
diff --git a/packages/svelte/tests/runtime-legacy/samples/reactive-value-assign-properties/main.svelte b/packages/svelte/tests/runtime-legacy/samples/reactive-value-assign-properties/main.svelte
new file mode 100644
index 0000000000..6dabf61707
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/reactive-value-assign-properties/main.svelte
@@ -0,0 +1,12 @@
+<script>
+	let button = { title: '', label: '' };
+	let title = '';
+	let label = '';
+
+	title = label = '1'; // to add dependencies/generate update block
+
+	$: button.title = title;
+	$: button.label = label;
+</script>
+
+{button.title} {button.label}