diff --git a/src/ocrmypdf/_validation.py b/src/ocrmypdf/_validation.py
index 58ea18bf..82a9cc35 100644
--- a/src/ocrmypdf/_validation.py
+++ b/src/ocrmypdf/_validation.py
@@ -133,7 +133,7 @@ def check_options_preprocessing(options):
                     options.unpaper_args
                 )
         except Exception as e:
-            raise BadArgsError("--unpaper-args") from e
+            raise BadArgsError("--unpaper-args: " + str(e)) from e
 
 
 def _pages_from_ranges(ranges: str) -> Set[int]: