diff --git a/app/tasks/convert_to_pdfa.py b/app/tasks/convert_to_pdfa.py
index b94ae74a..185b3f8f 100644
--- a/app/tasks/convert_to_pdfa.py
+++ b/app/tasks/convert_to_pdfa.py
@@ -78,6 +78,7 @@ def _convert_pdf_to_pdfa(input_path: str, output_path: str, pdfa_format: str = "
         output_type,
         "--quiet",
         "--invalidate-digital-signatures",
+        "--",  # end-of-options separator: prevents file paths from being interpreted as options
         input_path,
         output_path,
     ]