diff --git a/src/core/server/http/cookie_session_storage.test.ts b/src/core/server/http/cookie_session_storage.test.ts
index 4ce422e1f65c4..0ca87eae6e235 100644
--- a/src/core/server/http/cookie_session_storage.test.ts
+++ b/src/core/server/http/cookie_session_storage.test.ts
@@ -62,6 +62,7 @@ configService.atPath.mockReturnValue(
       disableProtection: true,
       whitelist: [],
     },
+    customResponseHeaders: {},
   } as any)
 );
 
diff --git a/src/core/server/http/test_utils.ts b/src/core/server/http/test_utils.ts
index 49c4d690c6876..0e639aa72a825 100644
--- a/src/core/server/http/test_utils.ts
+++ b/src/core/server/http/test_utils.ts
@@ -45,6 +45,7 @@ configService.atPath.mockReturnValue(
       disableProtection: true,
       whitelist: [],
     },
+    customResponseHeaders: {},
   } as any)
 );