diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4256077..4e0b4fb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,18 @@
 All notable changes to this project are documented here. This project adheres to
 [Semantic Versioning](https://semver.org/).
 
+## [4.0.3] - 2026-06-17
+
+### Fixed
+- **`setSource()` now invalidates rendered results.** Swapping the source while
+  the control was closed left the previous source's options in `this.results`;
+  the focus path's `!results.length` guard then skipped the re-search, so the
+  next open showed stale options (e.g. a dependent Country → Region dropdown
+  never refreshed). `setSource()` now clears `results`/`_total`/`activeIndex`
+  (matching `setScope()`), so the next open reflects the new source. The current
+  selection/value is left untouched. The `setScope({})` workaround is no longer
+  needed.
+
 ## [4.0.2] - 2026-06-17
 
 ### Docs
diff --git a/dist/liveselect.js b/dist/liveselect.js
index 4ee2fc4..32804f3 100644
--- a/dist/liveselect.js
+++ b/dist/liveselect.js
@@ -1043,7 +1043,14 @@
   /** Swap the data source (e.g. after pushing a new item to an array). */
   LiveSelect.prototype.setSource = function (source) {
     this.opts.source = source;
-    this._cache = {};   // results from the old source are no longer valid
+    // Invalidate everything rendered from the old source — otherwise a closed
+    // control keeps its stale results, and _onFocus's `!results.length` guard
+    // then skips the re-search on the next open. (The selection/value is left
+    // untouched; only the available options change.)
+    this.results = [];
+    this._total = null;
+    this.activeIndex = -1;
+    this._cache = {};
     if (this.isOpen) this._runSearch();
   };
 
diff --git a/package.json b/package.json
index dfaa9c7..c4b0e24 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@michaeljfalk/liveselect",
-  "version": "4.0.2",
+  "version": "4.0.3",
   "publishConfig": {
     "access": "public"
   },
diff --git a/test/client.test.js b/test/client.test.js
index 18e4f5b..564d650 100644
--- a/test/client.test.js
+++ b/test/client.test.js
@@ -518,3 +518,41 @@ test('enhance(<select multiple>) upgrades to multi and reflects back', { skip: !
   assert.deepEqual(selected, ['go', 'js', 'py'], 'reflected into the native <select multiple>');
   dd.destroy();
 });
+
+test('setSource() while closed refreshes the menu on next open (no stale options)', { skip: !domAvailable }, () => {
+  const host = mount();
+  const A = [{ value: 'a1', label: 'Apple' }, { value: 'a2', label: 'Apricot' }];
+  const B = [{ value: 'b1', label: 'Banana' }, { value: 'b2', label: 'Blueberry' }];
+  const dd = new LiveSelect(host, { source: A });
+
+  // Open once so results populate from A, then close.
+  dd.query = ''; dd.isOpen = true; dd._runSearch(); dd._renderMenu();
+  assert.equal(dd.results.length, 2);
+  dd.close();
+
+  // Swap the source while closed.
+  dd.setSource(B);
+  assert.deepEqual(dd.results, [], 'rendered results invalidated immediately');
+
+  // Re-open via the focus path → must reflect B, not stale A.
+  dd._onFocus();
+  dd._renderMenu();
+  const labels = Array.from(dd.menu.querySelectorAll('.liveselect__opt-label')).map((s) => s.textContent);
+  assert.deepEqual(labels, ['Banana', 'Blueberry'], 'menu lists the new source');
+  dd.destroy();
+});
+
+test('setSource() leaves the current selection/value intact', { skip: !domAvailable }, () => {
+  const host = mount();
+  const dd = new LiveSelect(host, {
+    name: 'fruit',
+    source: [{ value: 'a1', label: 'Apple' }],
+  });
+  dd._select({ value: 'a1', label: 'Apple', sublabel: '' });
+  assert.equal(dd.getValue(), 'a1');
+
+  dd.setSource([{ value: 'b1', label: 'Banana' }]);   // swap options only
+  assert.equal(dd.getValue(), 'a1', 'selected value survives the source swap');
+  assert.equal(host.querySelector('input[type=hidden][name=fruit]').value, 'a1');
+  dd.destroy();
+});