diff --git a/boards/utils.py b/boards/utils.py
--- a/boards/utils.py
+++ b/boards/utils.py
@@ -117,7 +117,7 @@ def get_file_hash(file) -> str:
 
 def validate_file_size(size: int):
     max_size = boards.settings.get_int('Forms', 'MaxFileSize')
-    if size > max_size:
+    if max_size > 0 and size > max_size:
         raise forms.ValidationError(
             _('File must be less than %s but is %s.')
             % (filesizeformat(max_size), filesizeformat(size)))