diff --git a/src/drive.ts b/src/drive.ts
index 504720f..e440a22 100644
--- a/src/drive.ts
+++ b/src/drive.ts
@@ -375,11 +375,16 @@ export class FileSystemDrive implements Contents.IDrive {
     let format: Contents.FileFormat;
     let fileContent: any = null;
 
-    // We assume here image, audio and video mimetypes are all and only binary files we'll encounter
+    // We assume here image, audio, video, zip and pdf mimetypes are all and only binary files we'll encounter
     if (
       file.type &&
-      file.type.split('/') &&
-      ['image', 'audio', 'video'].includes(file.type.split('/')[0])
+      ((file.type.split('/') &&
+        ['image', 'audio', 'video'].includes(file.type.split('/')[0])) ||
+        [
+          'application/zip',
+          'application/pdf',
+          'application/octet-stream'
+        ].includes(file.type))
     ) {
       format = 'base64';
     } else {