diff --git a/product/ERP5Form/ScribusUtils.py b/product/ERP5Form/ScribusUtils.py
index 1c917236fce6f83bb0f4efa8cdb8ef1b53caaecb..6b9f8ef48928e63b00e0fba07965e2cd9fda66c2 100644
--- a/product/ERP5Form/ScribusUtils.py
+++ b/product/ERP5Form/ScribusUtils.py
@@ -606,7 +606,7 @@ class ManageFiles:
       # check that the command has been done succeful
       if result[0] != 0:
         LOG('ScribusUtils.setBackgroundPictures :', ERROR, 'convert command'\
-            'failed with the following error message : \n%' % result[1])
+            'failed with the following error message : \n%s' % result[1])
         temp_image.close()
         raise
     finally: