diff --git a/src/ucis/merge/db_merger.py b/src/ucis/merge/db_merger.py
index 57cf7fd..b4749e7 100644
--- a/src/ucis/merge/db_merger.py
+++ b/src/ucis/merge/db_merger.py
@@ -86,10 +86,9 @@ def _merge_covergroups(self, dst_scope, src_scopes):
                 name = src_cg.getScopeName()
                 
                 if name not in cg_name_m.keys():
-                    scope_l = [None]*len(src_scopes)
-                    cg_name_m[name] = scope_l
-                    cg_name_l.append(name)
-                cg_name_m[name][i] = src_cg
+                  cg_name_m[name] = []
+                  cg_name_l.append(name)
+                cg_name_m[name].append(src_cg)
 
         for name in cg_name_l:                
             src_cg_l = list(filter(lambda cg: cg is not None, cg_name_m[name]))