diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index fda5bbad5c..799aafbd99 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -60,8 +60,8 @@ module ActiveRecord
         def create_database(name, options = {})
           options = { encoding: 'utf8' }.merge!(options.symbolize_keys)
 
-          option_string = options.sum do |key, value|
-            case key
+          option_string = options.inject("") do |memo, (key, value)|
+            memo += case key
             when :owner
               " OWNER = \"#{value}\""
             when :template