diff --git a/src/config/mock/auth.config.mock.ts b/src/config/mock/auth.config.mock.ts
index 9ffada095..cbac194e2 100644
--- a/src/config/mock/auth.config.mock.ts
+++ b/src/config/mock/auth.config.mock.ts
@@ -1,43 +1,48 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { registerAs } from '@nestjs/config';
 
-export default registerAs('authConfig', () => ({
-  session: {
-    secret: 'my_secret',
-    lifetime: 1209600000,
-  },
-  local: {
-    enableLogin: true,
-    enableRegister: true,
-  },
-  facebook: {
-    clientID: undefined,
-    clientSecret: undefined,
-  },
-  twitter: {
-    consumerKey: undefined,
-    consumerSecret: undefined,
-  },
-  github: {
-    clientID: undefined,
-    clientSecret: undefined,
-  },
-  dropbox: {
-    clientID: undefined,
-    clientSecret: undefined,
-    appKey: undefined,
-  },
-  google: {
-    clientID: undefined,
-    clientSecret: undefined,
-    apiKey: undefined,
-  },
-  gitlab: [],
-  ldap: [],
-  saml: [],
-  oauth2: [],
-}));
+import { AuthConfig } from '../auth.config';
+
+export default registerAs(
+  'authConfig',
+  (): AuthConfig => ({
+    session: {
+      secret: 'my_secret',
+      lifetime: 1209600000,
+    },
+    local: {
+      enableLogin: true,
+      enableRegister: true,
+    },
+    facebook: {
+      clientID: '',
+      clientSecret: '',
+    },
+    twitter: {
+      consumerKey: '',
+      consumerSecret: '',
+    },
+    github: {
+      clientID: '',
+      clientSecret: '',
+    },
+    dropbox: {
+      clientID: '',
+      clientSecret: '',
+      appKey: '',
+    },
+    google: {
+      clientID: '',
+      clientSecret: '',
+      apiKey: '',
+    },
+    gitlab: [],
+    ldap: [],
+    saml: [],
+    oauth2: [],
+  }),
+);
diff --git a/src/config/mock/customization.config.mock.ts b/src/config/mock/customization.config.mock.ts
index b9e7281e6..80d4b9a16 100644
--- a/src/config/mock/customization.config.mock.ts
+++ b/src/config/mock/customization.config.mock.ts
@@ -1,18 +1,23 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { registerAs } from '@nestjs/config';
 
-export default registerAs('customizationConfig', () => ({
-  branding: {
-    customName: 'ACME Corp',
-    customLogo: '',
-  },
-  specialUrls: {
-    privacy: '/test/privacy',
-    termsOfUse: '/test/termsOfUse',
-    imprint: '/test/imprint',
-  },
-}));
+import { CustomizationConfig } from '../customization.config';
+
+export default registerAs(
+  'customizationConfig',
+  (): CustomizationConfig => ({
+    branding: {
+      customName: 'ACME Corp',
+      customLogo: '',
+    },
+    specialUrls: {
+      privacy: '/test/privacy',
+      termsOfUse: '/test/termsOfUse',
+      imprint: '/test/imprint',
+    },
+  }),
+);
diff --git a/src/config/mock/external-services.config.mock.ts b/src/config/mock/external-services.config.mock.ts
index 736f37552..231b4a832 100644
--- a/src/config/mock/external-services.config.mock.ts
+++ b/src/config/mock/external-services.config.mock.ts
@@ -1,11 +1,16 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { registerAs } from '@nestjs/config';
 
-export default registerAs('externalServicesConfig', () => ({
-  plantUmlServer: 'plantuml.example.com',
-  imageProxy: 'imageProxy.example.com',
-}));
+import { ExternalServicesConfig } from '../external-services.config';
+
+export default registerAs(
+  'externalServicesConfig',
+  (): ExternalServicesConfig => ({
+    plantUmlServer: 'plantuml.example.com',
+    imageProxy: 'imageProxy.example.com',
+  }),
+);
diff --git a/src/config/mock/media.config.mock.ts b/src/config/mock/media.config.mock.ts
index b3e73eaf7..51320a272 100644
--- a/src/config/mock/media.config.mock.ts
+++ b/src/config/mock/media.config.mock.ts
@@ -1,16 +1,24 @@
 /*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { registerAs } from '@nestjs/config';
 
-export default registerAs('mediaConfig', () => ({
-  backend: {
-    use: 'filesystem',
-    filesystem: {
-      uploadPath:
-        'test_uploads' + Math.floor(Math.random() * 100000).toString(),
+import { BackendType } from '../../media/backends/backend-type.enum';
+import { MediaBackendConfig, MediaConfig } from '../media.config';
+
+export default registerAs(
+  'mediaConfig',
+  (): Omit<MediaConfig, 'backend'> & {
+    backend: Pick<MediaBackendConfig, 'use' | 'filesystem'>;
+  } => ({
+    backend: {
+      use: BackendType.FILESYSTEM,
+      filesystem: {
+        uploadPath:
+          'test_uploads' + Math.floor(Math.random() * 100000).toString(),
+      },
     },
-  },
-}));
+  }),
+);