diff --git a/src/compiler/compile/Component.ts b/src/compiler/compile/Component.ts
index 9822529ece..8203866642 100644
--- a/src/compiler/compile/Component.ts
+++ b/src/compiler/compile/Component.ts
@@ -780,7 +780,7 @@ export default class Component {
 
 		const component = this;
 		const { content } = script;
-		const { instance_scope, instance_scope_map: map } = this;
+		const { instance_scope, module_scope, instance_scope_map: map } = this;
 
 		let scope = instance_scope;
 
@@ -797,7 +797,13 @@ export default class Component {
 					const deep = assignee.type === 'MemberExpression';
 
 					names.forEach(name => {
-						if (scope.find_owner(name) === instance_scope) {
+						const scope_owner = scope.find_owner(name);
+						if (scope_owner !== null) {
+							if (scope_owner === instance_scope) {
+								const variable = component.var_lookup.get(name);
+								variable[deep ? 'mutated' : 'reassigned'] = true;
+							}
+						} else if (module_scope.has(name)) {
 							const variable = component.var_lookup.get(name);
 							variable[deep ? 'mutated' : 'reassigned'] = true;
 						}
diff --git a/test/vars/samples/modules-vars/_config.js b/test/vars/samples/modules-vars/_config.js
new file mode 100644
index 0000000000..e178941db6
--- /dev/null
+++ b/test/vars/samples/modules-vars/_config.js
@@ -0,0 +1,72 @@
+export default {
+	test(assert, vars) {
+		assert.deepEqual(vars, [
+			{
+				name: "a",
+				export_name: null,
+				injected: false,
+				module: true,
+				mutated: false,
+				reassigned: true,
+				referenced: false,
+				referenced_from_script: false,
+				writable: true
+			},
+			{
+				name: "b",
+				export_name: null,
+				injected: false,
+				module: true,
+				mutated: true,
+				reassigned: false,
+				referenced: false,
+				referenced_from_script: false,
+				writable: true
+			},
+			{
+				name: "c",
+				export_name: null,
+				injected: false,
+				module: true,
+				mutated: false,
+				reassigned: false,
+				referenced: false,
+				referenced_from_script: false,
+				writable: true
+			},
+			{
+				name: "d",
+				export_name: null,
+				injected: false,
+				module: true,
+				mutated: false,
+				reassigned: false,
+				referenced: false,
+				referenced_from_script: false,
+				writable: true
+			},
+			{
+				name: "c",
+				export_name: null,
+				injected: false,
+				module: false,
+				mutated: false,
+				reassigned: true,
+				referenced: false,
+				referenced_from_script: true,
+				writable: true
+			},
+			{
+				name: "foo",
+				export_name: null,
+				injected: false,
+				module: false,
+				mutated: false,
+				reassigned: false,
+				referenced: false,
+				referenced_from_script: false,
+				writable: false
+			}
+		]);
+	}
+};
diff --git a/test/vars/samples/modules-vars/input.svelte b/test/vars/samples/modules-vars/input.svelte
new file mode 100644
index 0000000000..8bbd5bdc5e
--- /dev/null
+++ b/test/vars/samples/modules-vars/input.svelte
@@ -0,0 +1,18 @@
+<script context='module'>
+	let a = {};
+	let b = {};
+	let c = {};
+	let d = {};
+</script>
+<script>
+	let c = {};
+
+	a = 1;
+	b.x = 1;
+
+	function foo() {
+		let d = {};
+		c = 1;
+		d.x = 1;
+	}
+</script>
\ No newline at end of file