diff --git a/python/obitools3/dms/view/view.pyx b/python/obitools3/dms/view/view.pyx
index 9b0980d..91fc8b3 100755
--- a/python/obitools3/dms/view/view.pyx
+++ b/python/obitools3/dms/view/view.pyx
@@ -263,7 +263,6 @@ cdef class View(OBIWrapper) :
 
 
     # TODO warning, not multithreading compliant
-    # TODO there is a bug when rewriting a partial line with None values
     cpdef Column rewrite_column_with_diff_attributes(self,
                                                      object    column_name,
                                                      obitype_t new_data_type=<obitype_t>OBI_VOID,
@@ -272,7 +271,7 @@ cdef class View(OBIWrapper) :
         
         cdef Column  old_column                                             
         cdef Column  new_column
-        cdef index_t length = len(self)
+        cdef index_t length = len(self) - 1
         cdef column_name_b = tobytes(column_name)
 
         if not self.active() :