diff --git a/frontend/src/api/apiClient.test.ts b/frontend/src/api/apiClient.test.ts
index a11a507..44a439f 100644
--- a/frontend/src/api/apiClient.test.ts
+++ b/frontend/src/api/apiClient.test.ts
@@ -49,7 +49,7 @@ describe("request interceptor", () => {
   });
 
   it("should not send Authorization header when the store has no token", async () => {
-    let capturedAuthHeader: string | null;
+    let capturedAuthHeader: string | null = "";
     server.use(
       http.get(`${API_URL}/api/auth/me/`, ({ request }) => {
         capturedAuthHeader = request.headers.get("Authorization");
diff --git a/frontend/src/utils/keystore.test.ts b/frontend/src/utils/keystore.test.ts
index 1398494..ea639c1 100644
--- a/frontend/src/utils/keystore.test.ts
+++ b/frontend/src/utils/keystore.test.ts
@@ -46,7 +46,7 @@ describe("keystore", () => {
     await saveMasterKey(key1);
     await saveMasterKey(key2);
     const loadedKey = await loadMasterKey();
-    const loadedJwk = await crypto.subtle.exportKey("jwk", loadedKey);
+    const loadedJwk = await crypto.subtle.exportKey("jwk", loadedKey!);
     const key1Jwk = await crypto.subtle.exportKey("jwk", key1);
     const key2Jwk = await crypto.subtle.exportKey("jwk", key2);