diff --git a/ts/test/types/Attachment_test.ts b/ts/test/types/Attachment_test.ts
index 343373d4ba..cdb671eed6 100644
--- a/ts/test/types/Attachment_test.ts
+++ b/ts/test/types/Attachment_test.ts
@@ -5,7 +5,7 @@ import 'mocha';
 import { assert } from 'chai';
 
 import * as Attachment from '../../types/Attachment';
-import { MIMEType } from '../../types/MIME';
+import * as MIME from '../../types/MIME';
 // @ts-ignore
 import { stringToArrayBuffer } from '../../../js/modules/string_to_array_buffer';
 
@@ -14,7 +14,7 @@ describe('Attachment', () => {
     it('should return file extension from content type', () => {
       const input: Attachment.Attachment = {
         data: stringToArrayBuffer('foo'),
-        contentType: 'image/gif' as MIMEType,
+        contentType: MIME.IMAGE_GIF,
       };
       assert.strictEqual(Attachment.getFileExtension(input), 'gif');
     });
@@ -22,7 +22,7 @@ describe('Attachment', () => {
     it('should return file extension for QuickTime videos', () => {
       const input: Attachment.Attachment = {
         data: stringToArrayBuffer('foo'),
-        contentType: 'video/quicktime' as MIMEType,
+        contentType: MIME.VIDEO_QUICKTIME,
       };
       assert.strictEqual(Attachment.getFileExtension(input), 'mov');
     });
@@ -34,7 +34,7 @@ describe('Attachment', () => {
         const attachment: Attachment.Attachment = {
           fileName: 'funny-cat.mov',
           data: stringToArrayBuffer('foo'),
-          contentType: 'video/quicktime' as MIMEType,
+          contentType: MIME.VIDEO_QUICKTIME,
         };
         const actual = Attachment.getSuggestedFilename({ attachment });
         const expected = 'funny-cat.mov';
@@ -45,7 +45,7 @@ describe('Attachment', () => {
       it('should generate a filename based on timestamp', () => {
         const attachment: Attachment.Attachment = {
           data: stringToArrayBuffer('foo'),
-          contentType: 'video/quicktime' as MIMEType,
+          contentType: MIME.VIDEO_QUICKTIME,
         };
         const timestamp = new Date(new Date(0).getTimezoneOffset() * 60 * 1000);
         const actual = Attachment.getSuggestedFilename({
diff --git a/ts/test/types/message/initializeAttachmentMetadata_test.ts b/ts/test/types/message/initializeAttachmentMetadata_test.ts
index d76618f280..9c87215f3b 100644
--- a/ts/test/types/message/initializeAttachmentMetadata_test.ts
+++ b/ts/test/types/message/initializeAttachmentMetadata_test.ts
@@ -3,7 +3,7 @@ import { assert } from 'chai';
 
 import * as Message from '../../../../ts/types/message/initializeAttachmentMetadata';
 import { IncomingMessage } from '../../../../ts/types/Message';
-import { MIMEType } from '../../../../ts/types/MIME';
+import * as MIME from '../../../../ts/types/MIME';
 // @ts-ignore
 import { stringToArrayBuffer } from '../../../../js/modules/string_to_array_buffer';
 
@@ -19,7 +19,7 @@ describe('Message', () => {
         sent_at: 1523317140800,
         attachments: [
           {
-            contentType: 'image/jpeg' as MIMEType,
+            contentType: MIME.IMAGE_JPEG,
             data: stringToArrayBuffer('foo'),
             fileName: 'foo.jpg',
             size: 1111,
@@ -35,7 +35,7 @@ describe('Message', () => {
         sent_at: 1523317140800,
         attachments: [
           {
-            contentType: 'image/jpeg' as MIMEType,
+            contentType: MIME.IMAGE_JPEG,
             data: stringToArrayBuffer('foo'),
             fileName: 'foo.jpg',
             size: 1111,
diff --git a/ts/types/MIME.ts b/ts/types/MIME.ts
index 43ed14efb0..60dd011558 100644
--- a/ts/types/MIME.ts
+++ b/ts/types/MIME.ts
@@ -1,8 +1,12 @@
 export type MIMEType = string & { _mimeTypeBrand: any };
 
+export const APPLICATION_OCTET_STREAM = 'application/octet-stream' as MIMEType;
+export const IMAGE_GIF = 'image/gif' as MIMEType;
+export const IMAGE_JPEG = 'image/jpeg' as MIMEType;
+export const VIDEO_QUICKTIME = 'video/quicktime' as MIMEType;
+
 export const isJPEG = (value: MIMEType): boolean => value === 'image/jpeg';
 export const isImage = (value: MIMEType): boolean => value.startsWith('image/');
 export const isVideo = (value: MIMEType): boolean => value.startsWith('video/');
 export const isAudio = (value: MIMEType): boolean => value.startsWith('audio/');
 
-export const APPLICATION_OCTET_STREAM = 'application/octet-stream' as MIMEType;