diff --git a/docker/web/nginx.conf b/docker/web/nginx.conf
index 012d6fa6..969cb6e1 100644
--- a/docker/web/nginx.conf
+++ b/docker/web/nginx.conf
@@ -6,6 +6,16 @@ upstream s3 {
 	server files:80 fail_timeout=0;
 }
 
+map $uri $custom_content_type {
+	default		"text/html";
+	~(.*\.png)$	"image/png";
+	~(.*\.jpe?g)$	"image/jpeg";
+	~(.*\.gif)$	"image/gif";
+	~(.*\.svg)$	"image/svg+xml";
+	~(.*\.mp4)$	"video/mp4";
+	~(.*\.webm)$	"video/webm";
+}
+
 server {
 	listen 80 default;
 	listen [::]:80;
@@ -19,6 +29,8 @@ server {
 		expires max;
 		add_header      Cache-Control public;
 		proxy_pass http://s3/$BUCKET_NAME/images/$1/$2/full.$3;
+		proxy_hide_header Content-Type;
+		add_header Content-Type $custom_content_type;
 	}
 
 	location ~ ^/img/download/(.+)/([0-9]+).*\.([A-Za-z0-9]+)$ {
@@ -26,36 +38,48 @@ server {
 		expires max;
 		add_header      Cache-Control public;
 		proxy_pass http://s3/$BUCKET_NAME/images/$1/$2/full.$3;
+		proxy_hide_header Content-Type;
+		add_header Content-Type $custom_content_type;
 	}
 
 	location ~ ^/img/(.+) {
 		expires max;
 		add_header Cache-Control public;
 		proxy_pass http://s3/$BUCKET_NAME/images/$1;
+		proxy_hide_header Content-Type;
+		add_header Content-Type $custom_content_type;
 	}
 
 	location ~ ^/spns/(.+) {
 		expires max;
 		add_header Cache-Control public;
 		proxy_pass http://s3/$BUCKET_NAME/adverts/$1;
+		proxy_hide_header Content-Type;
+		add_header Content-Type $custom_content_type;
 	}
 
 	location ~ ^/avatars/(.+) {
 		expires max;
 		add_header Cache-Control public;
 		proxy_pass http://s3/$BUCKET_NAME/avatars/$1;
+		proxy_hide_header Content-Type;
+		add_header Content-Type $custom_content_type;
 	}
 
 	location ~ ^/badges/(.+) {
 		expires max;
 		add_header Cache-Control public;
 		proxy_pass http://s3/$BUCKET_NAME/badges/$1;
+		proxy_hide_header Content-Type;
+		add_header Content-Type $custom_content_type;
 	}
 
 	location ~ ^/tags/(.+) {
 		expires max;
 		add_header Cache-Control public;
 		proxy_pass http://s3/$BUCKET_NAME/tags/$1;
+		proxy_hide_header Content-Type;
+		add_header Content-Type $custom_content_type;
 	}
 
 	location / {
diff --git a/lib/philomena/images/thumbnailer.ex b/lib/philomena/images/thumbnailer.ex
index 2f4236de..9d80a070 100644
--- a/lib/philomena/images/thumbnailer.ex
+++ b/lib/philomena/images/thumbnailer.ex
@@ -8,6 +8,7 @@ defmodule Philomena.Images.Thumbnailer do
   alias Philomena.Images.Image
   alias Philomena.Processors
   alias Philomena.Analyzers
+  alias Philomena.Uploader
   alias Philomena.Sha512
   alias Philomena.Repo
   alias ExAws.S3
@@ -131,10 +132,7 @@ defmodule Philomena.Images.Thumbnailer do
   def upload_file(image, file, version_name) do
     path = Path.join(image_thumb_prefix(image), version_name)
 
-    file
-    |> S3.Upload.stream_file()
-    |> S3.upload(bucket(), path, @acl)
-    |> ExAws.request!()
+    Uploader.persist_file(path, file)
   end
 
   defp bulk_rename(file_names, source_prefix, target_prefix) do
diff --git a/lib/philomena/uploader.ex b/lib/philomena/uploader.ex
index effb31a3..1b02a4b6 100644
--- a/lib/philomena/uploader.ex
+++ b/lib/philomena/uploader.ex
@@ -6,6 +6,7 @@ defmodule Philomena.Uploader do
   alias Philomena.Filename
   alias Philomena.Analyzers
   alias Philomena.Sha512
+  alias Philomena.Mime
   alias ExAws.S3
   import Ecto.Changeset
 
@@ -64,9 +65,19 @@ defmodule Philomena.Uploader do
     dest = Map.get(model, field(field_name))
     target = Path.join(file_root, dest)
 
-    source
+    persist_file(target, source)
+  end
+
+  @doc """
+  Persist an arbitrary file to storage at the given path with the correct
+  content type and permissions.
+  """
+  def persist_file(path, file) do
+    {_, mime} = Mime.file(path)
+
+    file
     |> S3.Upload.stream_file()
-    |> S3.upload(bucket(), target, acl: :public_read)
+    |> S3.upload(bucket(), path, acl: :public_read, content_type: mime)
     |> ExAws.request!()
   end