diff --git a/CHANGELOG.md b/CHANGELOG.md
index c9412df..25d40d0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,18 @@
 # Matemat Changelog
 
+<!-- BEGIN RELEASE v0.4.6 -->
+## Version 0.4.6
+
+Bugfix release
+
+### Changes
+
+<!-- BEGIN CHANGES 0.4.6 -->
+- fix: scale up thumbnails smaller than 300x300
+<!-- END CHANGES 0.4.6 -->
+
+<!-- END RELEASE v0.4.6 -->
+
 <!-- BEGIN RELEASE v0.4.5 -->
 ## Version 0.4.5
 
diff --git a/matemat/__init__.py b/matemat/__init__.py
index 7553f16..62c068b 100644
--- a/matemat/__init__.py
+++ b/matemat/__init__.py
@@ -1,2 +1,2 @@
 
-__version__ = '0.4.5'
+__version__ = '0.4.6'
diff --git a/matemat/util/thumbnails.py b/matemat/util/thumbnails.py
index 038fde7..811e27c 100644
--- a/matemat/util/thumbnails.py
+++ b/matemat/util/thumbnails.py
@@ -24,14 +24,17 @@ def upload_thumbnail(image_data: bytes, filename: str, size: int = 300) -> bool:
         image: Image = Image.open(BytesIO(image_data))
     except IOError:
         raise ValueError(f'Unsupported file type: {filemagic.mime_type}')
-    # Resize the image to 150x150
-    image.thumbnail((size, size), Image.LANCZOS)
+    # Resize the image preserving the aspect ratio
+    if image.width > image.height:
+        resized = image.resize((size, size*image.height//image.width), Image.LANCZOS)
+    else:
+        resized = image.resize((size*image.width//image.height, size), Image.LANCZOS)
 
-    # Create a new 150x150 transparent image and paste the thumbnail in the center
+    # Create a new square 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))
+    x = (thumb.width - resized.width) // 2
+    y = (thumb.height - resized.height) // 2
+    thumb.paste(resized, (x, y))
     # Write the image to the file
     thumb.save(filename, 'PNG')
     return True