diff --git a/.storybook/wcag/test-runner.ts b/.storybook/wcag/test-runner.ts
index c8183794f..161d244e2 100644
--- a/.storybook/wcag/test-runner.ts
+++ b/.storybook/wcag/test-runner.ts
@@ -7,33 +7,40 @@ import { TestContext, TestRunnerConfig } from '@storybook/test-runner';
  * See https://storybook.js.org/docs/react/writing-tests/test-runner#test-hook-api-experimental
  * to learn more about the test-runner hooks API.
  */
+// Mutex to serialize axe checks and avoid concurrency issues
+let axeLock: Promise<void> = Promise.resolve();
+
 const renderFunctions: TestRunnerConfig = {
   async preVisit(page: Page) {
     await injectAxe(page);
   },
   async postVisit(page: Page, context: TestContext) {
-    await checkA11y(
-      page,
-      {
-        exclude: [
-          '#root .mapboxgl-canvas-container',
-          '.mapboxgl-marker',
-          '.mapboxgl-popup-close-button'
-        ],
-      },
-      {
-        axeOptions: {
-          runOnly,
-          rules: {
-            'color-contrast': { enabled: context.name !== 'Loading' },
-          },
-        },
-        detailedReport: true,
-        detailedReportOptions: {
-          html: true,
+    // Serialize axe checks to avoid "Axe is already running" error
+    axeLock = axeLock.then(async () => {
+      await checkA11y(
+        page,
+        {
+          exclude: [
+            '#root .mapboxgl-canvas-container',
+            '.mapboxgl-marker',
+            '.mapboxgl-popup-close-button'
+          ],
         },
-      }
-    );
+        {
+          axeOptions: {
+            runOnly,
+            rules: {
+              'color-contrast': { enabled: context.name !== 'Loading' },
+            },
+          },
+          detailedReport: true,
+          detailedReportOptions: {
+            html: true,
+          },
+        }
+      );
+    });
+    await axeLock;
   },
 };