diff --git a/main.py b/main.py
index f5c17f3..e1d1955 100644
--- a/main.py
+++ b/main.py
@@ -72,7 +72,7 @@ def convert_pdf(filename, filetype, output_path, resolution=300):
             img.alpha_channel = 'remove'
 
             image_filename = os.path.splitext(os.path.basename(filename))[0]
-            image_filename = f'{image_filename}-{i}.{filetype}'
+            image_filename = f'{image_filename}-{i:03}.{filetype}'
             image_filename = os.path.join(output_path, image_filename)
 
             img.save(filename=image_filename)