diff --git a/python/obitools3/dms/taxo/taxo.pyx b/python/obitools3/dms/taxo/taxo.pyx
index 5ed5ef1..7a70551 100755
--- a/python/obitools3/dms/taxo/taxo.pyx
+++ b/python/obitools3/dms/taxo/taxo.pyx
@@ -228,7 +228,11 @@ cdef class Taxonomy(OBIWrapper) :
 
 
     cpdef write(self, object prefix) :
-        if obi_write_taxonomy(self._dms.pointer(), self.pointer(), tobytes(prefix)) < 0 :
+        cdef DMS dms
+        cdef OBIDMS_p dms_p
+        dms = self._dms
+        dms_p = dms.pointer()
+        if obi_write_taxonomy(dms_p, self.pointer(), tobytes(prefix)) < 0 :
             raise Exception("Error writing the taxonomy to binary files")