diff --git a/storages/s3_storage.py b/storages/s3_storage.py
index ceb75c1..b124aae 100644
--- a/storages/s3_storage.py
+++ b/storages/s3_storage.py
@@ -1,4 +1,4 @@
-import uuid, os
+import uuid, os, mimetypes
 from dataclasses import dataclass
 
 import boto3
@@ -21,6 +21,7 @@ class S3Config:
     private: bool = False
     key_path: str = "default"  # 'default' uses full naming, 'random' uses generated uuid
 
+
 class S3Storage(Storage):
 
     def __init__(self, config: S3Config):
@@ -70,4 +71,5 @@ class S3Storage(Storage):
             extra_args = kwargs.get("extra_args", {})
         else:
             extra_args = kwargs.get("extra_args", {'ACL': 'public-read'})
+        extra_args['ContentType'] = mimetypes.guess_type(key)[0]
         self.s3.upload_fileobj(file, Bucket=self.bucket, Key=self._get_path(key), ExtraArgs=extra_args)