diff --git a/synapse/media/thumbnailer.py b/synapse/media/thumbnailer.py
index d8979813b3..359b3233ef 100644
--- a/synapse/media/thumbnailer.py
+++ b/synapse/media/thumbnailer.py
@@ -51,7 +51,7 @@ class Thumbnailer:
         self._closed = False
 
         try:
-            self.image = Image.open(input_path)
+            self.image = Image.open(input_path, formats=["jpeg", "gif", "png"])
         except OSError as e:
             # If an error occurs opening the image, a thumbnail won't be able to
             # be generated.