diff --git a/lib/generators/closure_tree/templates/create_hierarchies_table.rb.erb b/lib/generators/closure_tree/templates/create_hierarchies_table.rb.erb
index 18d7671c..e85b2f3a 100644
--- a/lib/generators/closure_tree/templates/create_hierarchies_table.rb.erb
+++ b/lib/generators/closure_tree/templates/create_hierarchies_table.rb.erb
@@ -6,9 +6,12 @@ class <%= migration_class_name %> < ActiveRecord::Migration<%= migration_version
       t.integer :generations, null: false
     end
 
-    add_index :<%= migration_name %>, [:ancestor_id, :descendant_id, :generations],
+    add_index :<%= migration_name %>, [:ancestor_id, :descendant_id],
       unique: true,
-      name: "<%= file_name %>_anc_desc_idx"
+      name: "<%= file_name %>_anc_desc_uniq_idx"
+
+    add_index :<%= migration_name %>, [:ancestor_id, :descendant_id, :generations],
+      name: "<%= file_name %>_anc_desc_gene_idx"
 
     add_index :<%= migration_name -%>, [:descendant_id],
       name: "<%= file_name %>_desc_idx"
diff --git a/spec/support/schema.rb b/spec/support/schema.rb
index 94bdcbf3..58a7a785 100644
--- a/spec/support/schema.rb
+++ b/spec/support/schema.rb
@@ -34,8 +34,11 @@
     t.string 'name'
   end
 
-  add_index 'tag_hierarchies', %i[ancestor_id descendant_id generations], unique: true,
-                                                                          name: 'tag_anc_desc_idx'
+  add_index 'tag_hierarchies', %i[ancestor_id descendant_id], unique: true,
+                                                              name: 'tag_anc_desc_uniq_idx'
+
+  add_index 'tag_hierarchies', %i[ancestor_id descendant_id generations], name: 'tag_anc_desc_gene_idx'
+
   add_index 'tag_hierarchies', [:descendant_id], name: 'tag_desc_idx'
 
   create_table 'groups', force: true do |t|