diff --git a/matemat/webserver/pagelets/signup.py b/matemat/webserver/pagelets/signup.py
index 098abc1..042fde0 100644
--- a/matemat/webserver/pagelets/signup.py
+++ b/matemat/webserver/pagelets/signup.py
@@ -35,17 +35,19 @@ def signup_user(args: FormsDict, files: FormsDict, db: MatematDatabase) -> User:
     # Finally, set the avatar, if provided
     if 'avatar' in files:
         avatar = files.avatar.file.read()
-        if len(avatar) > 0:
-            filemagic: magic.FileMagic = magic.detect_from_content(avatar)
-            if filemagic.mime_type.startswith('image/'):
-                abspath: str = os.path.join(os.path.abspath(config['UploadDir']), 'thumbnails/users/')
-                os.makedirs(abspath, exist_ok=True)
-                # Parse the image data
-                image: Image = Image.open(BytesIO(avatar))
-                # Resize the image to 150x150
-                image.thumbnail((150, 150), Image.LANCZOS)
-                # Write the image to the file
-                image.save(os.path.join(abspath, f'{new_user.id}.png'), 'PNG')
+    else:
+        avatar = None
+    if avatar:
+        filemagic: magic.FileMagic = magic.detect_from_content(avatar)
+        if filemagic.mime_type.startswith('image/'):
+            abspath: str = os.path.join(os.path.abspath(config['UploadDir']), 'thumbnails/users/')
+            os.makedirs(abspath, exist_ok=True)
+            # Parse the image data
+            image: Image = Image.open(BytesIO(avatar))
+            # Resize the image to 150x150
+            image.thumbnail((150, 150), Image.LANCZOS)
+            # Write the image to the file
+            image.save(os.path.join(abspath, f'{new_user.id}.png'), 'PNG')
     else:
         # If a default avatar is set, copy it to the user's avatar path
         # Create the absolute path of the upload directory