diff --git a/packages/techdocs-common/__mocks__/@azure/storage-blob.ts b/packages/techdocs-common/__mocks__/@azure/storage-blob.ts
index 80c60acce7..b901f5f5a7 100644
--- a/packages/techdocs-common/__mocks__/@azure/storage-blob.ts
+++ b/packages/techdocs-common/__mocks__/@azure/storage-blob.ts
@@ -13,13 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import type {
+import {
   BlobUploadCommonResponse,
   ContainerGetPropertiesResponse,
 } from '@azure/storage-blob';
 import { EventEmitter } from 'events';
 
-const storage = new (global as any).StorageFilesMock();
+const storage = global.storageFilesMock;
 
 export class BlockBlobClient {
   private readonly blobName;
diff --git a/packages/techdocs-common/__mocks__/@google-cloud/storage.ts b/packages/techdocs-common/__mocks__/@google-cloud/storage.ts
index efc2454d08..856f09c4df 100644
--- a/packages/techdocs-common/__mocks__/@google-cloud/storage.ts
+++ b/packages/techdocs-common/__mocks__/@google-cloud/storage.ts
@@ -15,7 +15,7 @@
  */
 import { Readable } from 'stream';
 
-const storage = new (global as any).StorageFilesMock();
+const storage = global.storageFilesMock;
 
 class GCSFile {
   private readonly path: string;
diff --git a/packages/techdocs-common/__mocks__/aws-sdk.ts b/packages/techdocs-common/__mocks__/aws-sdk.ts
index 36c864bfe7..6251fe8357 100644
--- a/packages/techdocs-common/__mocks__/aws-sdk.ts
+++ b/packages/techdocs-common/__mocks__/aws-sdk.ts
@@ -18,7 +18,7 @@ import { ReadStream } from 'fs';
 
 export { Credentials } from 'aws-sdk';
 
-const storage = new (global as any).StorageFilesMock();
+const storage = global.storageFilesMock;
 
 export class S3 {
   constructor() {
diff --git a/packages/techdocs-common/__mocks__/globals.d.ts b/packages/techdocs-common/__mocks__/globals.d.ts
new file mode 100644
index 0000000000..ad293d2ebe
--- /dev/null
+++ b/packages/techdocs-common/__mocks__/globals.d.ts
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+declare module NodeJS {
+  interface Global {
+    rootDir: string;
+    storageFilesMock: IStorageFilesMock;
+  }
+}
diff --git a/packages/techdocs-common/__mocks__/types.d.ts b/packages/techdocs-common/__mocks__/types.d.ts
new file mode 100644
index 0000000000..e085b95851
--- /dev/null
+++ b/packages/techdocs-common/__mocks__/types.d.ts
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+interface IStorageFilesMock {
+  emptyFiles(): void;
+  fileExists(targetPath: string): boolean;
+  readFile(targetPath: string): Buffer;
+  writeFile(targetPath: string, sourcePath: string): void;
+  writeFile(targetPath: string, sourceBuffer: Buffer): void;
+  writeFile(targetPath: string, source: string | Buffer): void;
+}
diff --git a/packages/techdocs-common/src/globals.d.ts b/packages/techdocs-common/src/globals.d.ts
new file mode 100644
index 0000000000..ad293d2ebe
--- /dev/null
+++ b/packages/techdocs-common/src/globals.d.ts
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+declare module NodeJS {
+  interface Global {
+    rootDir: string;
+    storageFilesMock: IStorageFilesMock;
+  }
+}
diff --git a/packages/techdocs-common/src/setupTests.ts b/packages/techdocs-common/src/setupTests.ts
index 996a8d35dd..9a13e57633 100644
--- a/packages/techdocs-common/src/setupTests.ts
+++ b/packages/techdocs-common/src/setupTests.ts
@@ -18,18 +18,18 @@ import os from 'os';
 import path from 'path';
 import fs from 'fs-extra';
 
-const rootDir = os.platform() === 'win32' ? 'C:\\rootDir' : '/rootDir';
+const rootDir: string = os.platform() === 'win32' ? 'C:\\rootDir' : '/rootDir';
 
 const encoding = 'utf8';
 
-export class StorageFilesMock {
+class StorageFilesMock implements IStorageFilesMock {
   private files: Record<string, string>;
 
   constructor() {
     this.files = {};
   }
 
-  public emptyFiles() {
+  public emptyFiles(): void {
     this.files = {};
   }
 
@@ -56,6 +56,5 @@ export class StorageFilesMock {
   }
 }
 
-const _global = global as any;
-_global.rootDir = rootDir;
-_global.StorageFilesMock = StorageFilesMock;
+global.rootDir = rootDir;
+global.storageFilesMock = new StorageFilesMock();
diff --git a/packages/techdocs-common/src/stages/publish/awsS3.test.ts b/packages/techdocs-common/src/stages/publish/awsS3.test.ts
index d77d643291..62ec80d634 100644
--- a/packages/techdocs-common/src/stages/publish/awsS3.test.ts
+++ b/packages/techdocs-common/src/stages/publish/awsS3.test.ts
@@ -26,7 +26,7 @@ import { AwsS3Publish } from './awsS3';
 
 // NOTE: /packages/techdocs-common/__mocks__ is being used to mock aws-sdk client library
 
-const rootDir = (global as any).rootDir;
+const rootDir = global.rootDir;
 
 const getEntityRootDir = (entity: Entity) => {
   const {
diff --git a/packages/techdocs-common/src/stages/publish/azureBlobStorage.test.ts b/packages/techdocs-common/src/stages/publish/azureBlobStorage.test.ts
index dd658440d6..c32ec310d0 100644
--- a/packages/techdocs-common/src/stages/publish/azureBlobStorage.test.ts
+++ b/packages/techdocs-common/src/stages/publish/azureBlobStorage.test.ts
@@ -26,7 +26,7 @@ import { AzureBlobStoragePublish } from './azureBlobStorage';
 
 // NOTE: /packages/techdocs-common/__mocks__ is being used to mock Azure client library
 
-const rootDir = (global as any).rootDir;
+const rootDir = global.rootDir;
 
 const getEntityRootDir = (entity: Entity) => {
   const {
diff --git a/packages/techdocs-common/src/stages/publish/googleStorage.test.ts b/packages/techdocs-common/src/stages/publish/googleStorage.test.ts
index 57fde767ba..fe93ef909b 100644
--- a/packages/techdocs-common/src/stages/publish/googleStorage.test.ts
+++ b/packages/techdocs-common/src/stages/publish/googleStorage.test.ts
@@ -26,7 +26,7 @@ import { GoogleGCSPublish } from './googleStorage';
 
 // NOTE: /packages/techdocs-common/__mocks__ is being used to mock Google Cloud Storage client library
 
-const rootDir = (global as any).rootDir;
+const rootDir = global.rootDir;
 
 const getEntityRootDir = (entity: Entity) => {
   const {
diff --git a/packages/techdocs-common/src/types.d.ts b/packages/techdocs-common/src/types.d.ts
new file mode 100644
index 0000000000..e085b95851
--- /dev/null
+++ b/packages/techdocs-common/src/types.d.ts
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+interface IStorageFilesMock {
+  emptyFiles(): void;
+  fileExists(targetPath: string): boolean;
+  readFile(targetPath: string): Buffer;
+  writeFile(targetPath: string, sourcePath: string): void;
+  writeFile(targetPath: string, sourceBuffer: Buffer): void;
+  writeFile(targetPath: string, source: string | Buffer): void;
+}