diff --git a/pycdt/core/defectsmaker.py b/pycdt/core/defectsmaker.py
index 820911a..5492203 100644
--- a/pycdt/core/defectsmaker.py
+++ b/pycdt/core/defectsmaker.py
@@ -18,7 +18,6 @@
 import abc
 
 
-#from monty.string import str2unicode
 from monty.serialization import dumpfn
 from pymatgen.core.structure import PeriodicSite, Structure
 from pymatgen.core.periodic_table import Element, Specie, get_el_sp
@@ -246,7 +245,7 @@ def __init__(self, structure):
         self.oxi_states = {}
         for key,val in oxi_states.items():
             strip_key = ''.join([s for s in key if s.isalpha()])
-            self.oxi_states[str2unicode(strip_key)] = val
+            self.oxi_states[strip_key] = val
 
         self.min_max_oxi = {}
         for s in struct_species:
@@ -258,7 +257,7 @@ def __init__(self, structure):
                 continue
             max_oxi = max(el.common_oxidation_states)
             min_oxi = min(el.common_oxidation_states)
-            self.min_max_oxi[str2unicode(el.symbol)] = (min_oxi,max_oxi)
+            self.min_max_oxi[el.symbol] = (min_oxi,max_oxi)
         
     def get_charges(self, defect_type, site_specie=None, sub_specie=None):
         """
@@ -274,7 +273,7 @@ def get_charges(self, defect_type, site_specie=None, sub_specie=None):
         """
         if defect_type == 'vacancy':
             vac_symbol = get_el_sp(site_specie).symbol
-            vac_oxi_state = self.oxi_states[str2unicode(vac_symbol)]
+            vac_oxi_state = self.oxi_states[vac_symbol]
             if vac_oxi_state < 0:
                 min_oxi = max(vac_oxi_state, self.min_max_oxi[vac_symbol][0])
                 max_oxi = 0
@@ -289,7 +288,7 @@ def get_charges(self, defect_type, site_specie=None, sub_specie=None):
 
         elif defect_type == 'antisite':
             vac_symbol = get_el_sp(site_specie).symbol
-            vac_oxi_state = self.oxi_states[str2unicode(vac_symbol)]
+            vac_oxi_state = self.oxi_states[vac_symbol]
             as_symbol = get_el_sp(sub_specie).symbol
             if vac_oxi_state > 0:
                 oxi_max = max(self.min_max_oxi[as_symbol][1],0)
@@ -304,7 +303,7 @@ def get_charges(self, defect_type, site_specie=None, sub_specie=None):
             site_specie = get_el_sp(site_specie)
             sub_specie = get_el_sp(sub_specie)
             vac_symbol = site_specie.symbol
-            vac_oxi_state = self.oxi_states[str2unicode(vac_symbol)]
+            vac_oxi_state = self.oxi_states[vac_symbol]
 
             max_oxi_sub = max(sub_specie.common_oxidation_states)
             min_oxi_sub = min(sub_specie.common_oxidation_states)
@@ -352,7 +351,7 @@ def __init__(self, structure):
         self.oxi_states = {}
         for key,val in oxi_states.items():
             strip_key = ''.join([s for s in key if s.isalpha()])
-            self.oxi_states[str2unicode(strip_key)] = val
+            self.oxi_states[strip_key] = val
 
     def get_charges(self, defect_type, site_specie=None, sub_specie=None):
         """
@@ -368,7 +367,7 @@ def get_charges(self, defect_type, site_specie=None, sub_specie=None):
         """
         if defect_type == 'vacancy':
             vac_symbol = get_el_sp(site_specie).symbol
-            vac_oxi_state = self.oxi_states[str2unicode(vac_symbol)]
+            vac_oxi_state = self.oxi_states[vac_symbol]
             if vac_oxi_state == 0:
                 return [-1,0,1]
             else:
@@ -379,9 +378,9 @@ def get_charges(self, defect_type, site_specie=None, sub_specie=None):
         elif defect_type in ['antisite', 'substitution']:
             #TODO: may cause some weird states for substitutions. Worth updating in future.
             vac_symbol = get_el_sp(site_specie).symbol
-            vac_oxi_state = self.oxi_states[str2unicode(vac_symbol)]
+            vac_oxi_state = self.oxi_states[vac_symbol]
             as_symbol = get_el_sp(sub_specie).symbol
-            as_oxi_state = self.oxi_states[str2unicode(as_symbol)]
+            as_oxi_state = self.oxi_states[as_symbol]
             expected_oxi = as_oxi_state - vac_oxi_state
             if expected_oxi == 0:
                 return [-1,0,1]
@@ -565,7 +564,7 @@ def __init__(self, structure,  max_min_oxi=None, substitutions=None,
         self.substitutions = {}
         self.struct_type = struct_type
         for key, val in substitutions.items():
-            self.substitutions[str2unicode(key)] = val
+            self.substitutions[key] = val
 
         spa = SpacegroupAnalyzer(structure, symprec=1e-2)
         prim_struct = spa.get_primitive_standard_structure()