2 files changed, 8 insertions, 6 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 73aaffc146..17dd71e898 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -629,11 +629,13 @@ module ActiveRecord
               index_options = options[:where] ? " WHERE #{options[:where]}" : ""
             end
           else
-            message = "Passing a string as third argument of `add_index` is deprecated and will" +
-              " be removed in Rails 4.1." +
-              " Use add_index(#{table_name.inspect}, #{column_name.inspect}, unique: true) instead"
+            if options
+              message = "Passing a string as third argument of `add_index` is deprecated and will" +
+                " be removed in Rails 4.1." +
+                " Use add_index(#{table_name.inspect}, #{column_name.inspect}, unique: true) instead"
 
-            ActiveSupport::Deprecation.warn message
+              ActiveSupport::Deprecation.warn message
+            end
 
             index_type = options
           end
diff --git a/activerecord/test/cases/migration/references_statements_test.rb b/activerecord/test/cases/migration/references_statements_test.rb
index 144302bd4a..d8a6565d54 100644
--- a/activerecord/test/cases/migration/references_statements_test.rb
+++ b/activerecord/test/cases/migration/references_statements_test.rb
@@ -64,7 +64,7 @@ module ActiveRecord
         remove_reference table_name, :supplier
         refute index_exists?(table_name, :supplier_id)
       end
-      
+
       def test_does_not_delete_reference_type_column
         with_polymorphic_column do
           remove_reference table_name, :supplier
@@ -73,7 +73,7 @@ module ActiveRecord
           assert column_exists?(table_name, :supplier_type, :string)
         end
       end
-      
+
       def test_deletes_reference_type_column
         with_polymorphic_column do
           remove_reference table_name, :supplier, polymorphic: true