diff --git a/aiida_kkr/tools/tools_STM_scan.py b/aiida_kkr/tools/tools_STM_scan.py
index 98074f1c..a38a878a 100644
--- a/aiida_kkr/tools/tools_STM_scan.py
+++ b/aiida_kkr/tools/tools_STM_scan.py
@@ -137,7 +137,11 @@ def get_imp_info_add_position(add_position, host_structure, imp_info):
         #raise ValueError('Additional position exists already in impurity cluster.')
     cluster_combined, rimp_rel_combined, _, _ = combine_clusters(clust1, clust2_offset, False, debug=False)
     # combine the zimp arrays
-    zimp_combined = imp_info['Zimp'] + imp_info2['Zimp']
+    zimp1 = imp_info['Zimp']
+    if not isinstance(zimp1, list):
+        # convert to list if necessary
+        zimp1 = [zimp1]
+    zimp_combined = zimp1 + imp_info2['Zimp']
     # now combine the imp info node
     imp_info_combined = orm.Dict({'imp_cls': cluster_combined, 'Zimp': zimp_combined, 'Rimp_rel': rimp_rel_combined})
 
diff --git a/aiida_kkr/workflows/kkr_STM.py b/aiida_kkr/workflows/kkr_STM.py
index 75d4432c..f076ace1 100644
--- a/aiida_kkr/workflows/kkr_STM.py
+++ b/aiida_kkr/workflows/kkr_STM.py
@@ -33,7 +33,7 @@ class kkr_STM_wc(WorkChain):
         :param kkr: (Code), KKR host code for the writing out kkrflex files
         :param kkrimp: (Code), KKR impurity code for the normal state impurity scf and BdG impurity DOS calculation
         :param gf_writeout.params_kkr_overwrite (Dict), overwrite parameters for the GF calculation
-        :param kkr_imp_sub.params_kkr_overwrite (Dict), overwrite parameters for the impurity calculation
+        :param kkr_imp_sub.params_overwrite (Dict), overwrite parameters for the impurity calculation
 
      returns::
 
@@ -499,8 +499,8 @@ def STM_lmdos_run(self):
 
         # Update the BdG parameters if they are inserted in the workflow
         if 'BdG' in self.inputs:
-            if 'params_kkr_overwrite' in self.inputs.BdG:
-                builder.BdG.params_overwrite = self.inputs.BdG.params_kkr_overwrite  # pylint: disable=no-member
+            if 'params_overwrite' in self.inputs.BdG:
+                builder.BdG.params_overwrite = self.inputs.BdG.params_overwrite  # pylint: disable=no-member
 
         self.ctx.kkrimp_params_dict = Dict(
             dict={
@@ -559,8 +559,8 @@ def STM_lmdos_run(self):
 
         # print report
         message = f"""INFO: running DOS step for an STM measurement (pk: {calc.pk}) at position (ilayer: {self.inputs.tip_position['ilayer']})"""
-        if 'params_kkr_overwrite' in self.inputs.BdG:
-            if self.inputs.BdG.params_kkr_overwrite:
+        if 'params_overwrite' in self.inputs.BdG:
+            if self.inputs.BdG.params_overwrite:
                 message += f'\nINFO: runnig DOS step (pk: {calc.pk}) BdG is present'
         self.report(message)