diff --git a/db/migrate/6_add_missing_indexes_on_taggings.rb b/db/migrate/6_add_missing_indexes_on_taggings.rb
index 8345ae33b..72660cecb 100644
--- a/db/migrate/6_add_missing_indexes_on_taggings.rb
+++ b/db/migrate/6_add_missing_indexes_on_taggings.rb
@@ -1,12 +1,17 @@
 class AddMissingIndexesOnTaggings < ActiveRecord::Migration
   def change
-    add_index :taggings, :tag_id
-    add_index :taggings, :taggable_id
-    add_index :taggings, :taggable_type
-    add_index :taggings, :tagger_id
-    add_index :taggings, :context
+    add_index :taggings, :tag_id unless index_exists? :taggings, :tag_id
+    add_index :taggings, :taggable_id unless index_exists? :taggings, :taggable_id
+    add_index :taggings, :taggable_type unless index_exists? :taggings, :taggable_type
+    add_index :taggings, :tagger_id unless index_exists? :taggings, :tagger_id
+    add_index :taggings, :context unless index_exists? :taggings, :context
 
-    add_index :taggings, [:tagger_id, :tagger_type]
-    add_index :taggings, [:taggable_id, :taggable_type, :tagger_id, :context], name: 'taggings_idy'
+    unless index_exists? :taggings, [:tagger_id, :tagger_type]
+      add_index :taggings, [:tagger_id, :tagger_type]
+    end
+
+    unless index_exists? :taggings, [:taggable_id, :taggable_type, :tagger_id, :context], name: 'taggings_idy'
+      add_index :taggings, [:taggable_id, :taggable_type, :tagger_id, :context], name: 'taggings_idy'
+    end
   end
 end