diff --git a/matemat/util/thumbnails.py b/matemat/util/thumbnails.py
index 683d7c3..038fde7 100644
--- a/matemat/util/thumbnails.py
+++ b/matemat/util/thumbnails.py
@@ -7,7 +7,7 @@ import magic
 from PIL import Image
 
 
-def upload_thumbnail(image_data: bytes, filename: str, size: int = 150) -> bool:
+def upload_thumbnail(image_data: bytes, filename: str, size: int = 300) -> bool:
     # Only process the image, if its size is more than zero.  Zero size means no new image was uploaded
     if image_data is None or len(image_data) == 0:
         return False
@@ -25,7 +25,13 @@ def upload_thumbnail(image_data: bytes, filename: str, size: int = 150) -> bool:
     except IOError:
         raise ValueError(f'Unsupported file type: {filemagic.mime_type}')
     # Resize the image to 150x150
-    image.thumbnail((150, 150), Image.LANCZOS)
+    image.thumbnail((size, size), Image.LANCZOS)
+
+    # Create a new 150x150 transparent image and paste the thumbnail in the center
+    thumb: Image = Image.new('RGBA', (size, size), (0, 0, 0, 0))
+    x = (thumb.width - image.width) // 2
+    y = (thumb.height - image.height) // 2
+    thumb.paste(image, (x, y))
     # Write the image to the file
-    image.save(filename, 'PNG')
+    thumb.save(filename, 'PNG')
     return True
diff --git a/templates/moduser.html b/templates/moduser.html
index 16d85bd..38b12c3 100644
--- a/templates/moduser.html
+++ b/templates/moduser.html
@@ -49,7 +49,7 @@
         <input class="form-control" id="moduser-account-balance-reason" type="text" name="reason" placeholder="Shows up on receipt" /><br/>
 
         <label class="form-label" for="moduser-account-avatar">
-            <img src="/static/upload/thumbnails/users/{{ user.id }}.png?cacheBuster={{ now }}" alt="Avatar of {{ user.name }}" />
+            <img height="150" src="/static/upload/thumbnails/users/{{ user.id }}.png?cacheBuster={{ now }}" alt="Avatar of {{ user.name }}" />
         </label><br/>
         <input class="form-control" id="moduser-account-avatar" type="file" name="avatar" accept="image/*" /><br/>