diff --git a/classes/MarketImage.class.php b/classes/MarketImage.class.php
index 1e87af1759096a0db04c325b0d6fefce206fa01b..7fb8eae85c81b6725959b37d41bb5159fdcb1df8 100644
--- a/classes/MarketImage.class.php
+++ b/classes/MarketImage.class.php
@@ -45,7 +45,7 @@ class MarketImage extends SimpleORMap {
 
     public function outputImage() {
         $path = self::getImageDataPath() . "/" . $this->getId();
-        header("Content-Type: " . mime_content_type($path));
+        header("Content-Type: " . $this['mimetype']);
         header("Content-Disposition: inline; filename=" . $this['filename']);
         echo file_get_contents($path);
     }
diff --git a/controllers/myplugins.php b/controllers/myplugins.php
index d47da972e70045debbcd6e8f5a6662a4a2a1a14f..18b3958089aa9c4db4694e586c906c6606b6ff64 100644
--- a/controllers/myplugins.php
+++ b/controllers/myplugins.php
@@ -112,7 +112,7 @@ class MypluginsController extends PluginController {
                     $file = new MarketImage();
                     $file['plugin_id'] = $this->marketplugin->getId();
                     $file['filename'] = $name;
-                    $file['mimetype'] = $files['type'][$index];
+                    $file['mimetype'] = mime_content_type($files['tmp_name'][$index]);
                     $file['position'] = $position;
                     $file->installFromPath($files['tmp_name'][$index]);
                     $file->store();
diff --git a/controllers/presenting.php b/controllers/presenting.php
index a79da242c98f1a5e86f3feb0237208c9e34459a7..7b113e34010cb285b77ab9741e242f5f9341c3ca 100644
--- a/controllers/presenting.php
+++ b/controllers/presenting.php
@@ -155,7 +155,10 @@ class PresentingController extends PluginController {
 
     public function image_action($image_id) {
         $this->image = new MarketImage($image_id);
+
+        $this->set_content_type($this->image['mimetype']);
         $this->image->outputImage();
+
         $this->render_nothing();
     }