diff --git a/python/obitools3/dms/column/typed_column/str.pyx b/python/obitools3/dms/column/typed_column/str.pyx
index 89a183f..d39ceab 100644
--- a/python/obitools3/dms/column/typed_column/str.pyx
+++ b/python/obitools3/dms/column/typed_column/str.pyx
@@ -13,7 +13,7 @@ from ...capi.obiview cimport obi_get_str_with_elt_name_and_col_p_in_view, \
                              obi_set_str_with_elt_idx_and_col_p_in_view
 
 from ...capi.obierrno     cimport obi_errno
-from ...capi.obitypes     cimport OBI_STR, OBIStr_NA
+from ...capi.obitypes     cimport OBI_STR, OBIStr_NA, const_char_p
 
 
 cdef class Column_str(Column):
@@ -32,8 +32,8 @@ cdef class Column_str(Column):
 
 
     cpdef object get_line(self, index_t line_nb):
-        cdef char*  value
-        cdef object result
+        cdef const_char_p value
+        cdef object       result
         global      obi_errno
         value = obi_get_str_with_elt_idx_and_col_p_in_view(self._view.pointer(), self.pointer(), line_nb, 0)
         if obi_errno > 0 :
@@ -58,9 +58,9 @@ cdef class Column_str(Column):
 cdef class Column_multi_elts_str(Column_multi_elts):
  
     cpdef object get_item(self, index_t line_nb, object elt_id) :
-        cdef char*  value
-        cdef object result
-        global      obi_errno
+        cdef const_char_p value
+        cdef object       result
+        global            obi_errno
         if type(elt_id) == int :
             value = obi_get_str_with_elt_idx_and_col_p_in_view(self._view.pointer(), self.pointer(), line_nb, elt_id)
         else :
@@ -76,12 +76,12 @@ cdef class Column_multi_elts_str(Column_multi_elts):
 
 
     cpdef object get_line(self, index_t line_nb) :
-        cdef char*   value
-        cdef object  value_in_result
-        cdef dict    result
-        cdef index_t i
-        cdef bint    all_NA
-        global      obi_errno
+        cdef const_char_p value
+        cdef object       value_in_result
+        cdef dict         result
+        cdef index_t      i
+        cdef bint         all_NA
+        global            obi_errno
         result = {}
         all_NA = True
         for i in range(self.nb_elements_per_line) :