diff --git a/.changeset/four-tables-fix.md b/.changeset/four-tables-fix.md
new file mode 100644
index 0000000000..f17f57e253
--- /dev/null
+++ b/.changeset/four-tables-fix.md
@@ -0,0 +1,5 @@
+---
+'@backstage/backend-test-utils': patch
+---
+
+Added explicit return type signature for `mockServices.config()`.
diff --git a/packages/backend-test-utils/api-report.md b/packages/backend-test-utils/api-report.md
index 6e0edde88b..672c574cb2 100644
--- a/packages/backend-test-utils/api-report.md
+++ b/packages/backend-test-utils/api-report.md
@@ -6,7 +6,6 @@
 import { Backend } from '@backstage/backend-app-api';
 import { BackendFeature } from '@backstage/backend-plugin-api';
 import { CacheService } from '@backstage/backend-plugin-api';
-import { ConfigReader } from '@backstage/config';
 import { ConfigService } from '@backstage/backend-plugin-api';
 import { DatabaseService } from '@backstage/backend-plugin-api';
 import { ExtendedHttpServer } from '@backstage/backend-app-api';
@@ -37,7 +36,7 @@ export namespace mockServices {
       factory: () => ServiceFactory<CacheService>;
   }
   // (undocumented)
-  export function config(options?: config.Options): ConfigReader;
+  export function config(options?: config.Options): ConfigService;
   // (undocumented)
   export namespace config {
     // (undocumented)
diff --git a/packages/backend-test-utils/src/next/services/mockServices.ts b/packages/backend-test-utils/src/next/services/mockServices.ts
index ef32993611..5f771f13c5 100644
--- a/packages/backend-test-utils/src/next/services/mockServices.ts
+++ b/packages/backend-test-utils/src/next/services/mockServices.ts
@@ -15,6 +15,7 @@
  */
 
 import {
+  ConfigService,
   coreServices,
   createServiceFactory,
   IdentityService,
@@ -56,7 +57,7 @@ function simpleFactory<TService, TOptions extends [options?: object] = []>(
  * @alpha
  */
 export namespace mockServices {
-  export function config(options?: config.Options) {
+  export function config(options?: config.Options): ConfigService {
     return new ConfigReader(options?.data, 'mock-config');
   }
   export namespace config {