diff --git a/src/services/__tests__/firefox-api.test.ts b/src/services/__tests__/firefox-api.test.ts
new file mode 100644
index 0000000..7458131
--- /dev/null
+++ b/src/services/__tests__/firefox-api.test.ts
@@ -0,0 +1,53 @@
+import { afterAll, beforeEach, describe, expect, it, spyOn } from "bun:test";
+
+import { createFirefoxApi } from "../firefox-api";
+
+const fetchSpy = spyOn(globalThis, "fetch");
+
+const addonResponse = (overrides: Record<string, unknown> = {}) => ({
+  id: 123,
+  slug: "example-addon",
+  guid: "example-addon@example.com",
+  icon_url: "https://addons.mozilla.org/user-media/addon_icons/0/123-64.png",
+  last_updated: "2026-09-30T00:00:00Z",
+  description: { "en-US": "Long description" },
+  name: { "en-US": "Example Addon" },
+  summary: { "en-US": "Short description" },
+  ratings: { average: 5, bayesian_average: 5, count: 1, text_count: 1 },
+  url: "https://addons.mozilla.org/en-US/firefox/addon/example-addon/",
+  current_version: { version: "1.0.0" },
+  average_daily_users: 3,
+  previews: [],
+  ...overrides,
+});
+
+describe("Firefox API", () => {
+  beforeEach(() => {
+    fetchSpy.mockReset();
+  });
+
+  afterAll(() => {
+    fetchSpy.mockRestore();
+  });
+
+  it("should return the first localized value for each text field", async () => {
+    fetchSpy.mockResolvedValue(Response.json(addonResponse()));
+
+    const addon = await createFirefoxApi().getAddon("example-addon");
+
+    expect(addon.name).toBe("Example Addon");
+    expect(addon.shortDescription).toBe("Short description");
+    expect(addon.longDescription).toBe("Long description");
+  });
+
+  // AMO returns `null` instead of a locale map when the listing leaves a field empty
+  it("should return an empty string when a localized field is null", async () => {
+    fetchSpy.mockResolvedValue(Response.json(addonResponse({ description: null, summary: null })));
+
+    const addon = await createFirefoxApi().getAddon("example-addon");
+
+    expect(addon.name).toBe("Example Addon");
+    expect(addon.shortDescription).toBe("");
+    expect(addon.longDescription).toBe("");
+  });
+});
diff --git a/src/services/firefox-api.ts b/src/services/firefox-api.ts
index ceac978..52f4fa1 100644
--- a/src/services/firefox-api.ts
+++ b/src/services/firefox-api.ts
@@ -11,17 +11,21 @@ export interface FirefoxApi {
 }
 
 export function createFirefoxApi(): FirefoxApi {
+  // AMO returns `null` instead of a locale map when a listing leaves a field empty
+  const firstLocalizedValue = (value: { [locale: string]: string } | null): string =>
+    Object.values(value ?? {})[0] ?? "";
+
   const toGqlFirefoxAddon = (res: GetAddon200Response): Gql.FirefoxAddon => ({
     id: String(res.id),
     slug: res.slug,
     guid: res.guid,
     iconUrl: res.icon_url,
     lastUpdated: res.last_updated,
-    longDescription: Object.values<string>(res.description)[0]!,
-    name: Object.values<string>(res.name)[0]!,
+    longDescription: firstLocalizedValue(res.description),
+    name: firstLocalizedValue(res.name),
     rating: res.ratings.average,
     reviewCount: res.ratings.count,
-    shortDescription: Object.values<string>(res.summary)[0]!,
+    shortDescription: firstLocalizedValue(res.summary),
     storeUrl: res.url,
     version: res.current_version.version,
     users: res.average_daily_users,
@@ -105,7 +109,7 @@ type GetAddon200Response = {
   default_locale: string;
   description: {
     [locale: string]: string;
-  };
+  } | null;
   developer_comments: string | null;
   edit_url: string;
   guid: string;
@@ -153,7 +157,7 @@ type GetAddon200Response = {
   status: string;
   summary: {
     [locale: string]: string;
-  };
+  } | null;
   support_email: {
     [locale: string]: string;
   };