diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 731c07547af16ce32ea525760789653a65598c8e..64f922b7ad0838e239ebd192c6f219030ee001d9 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -526,7 +526,7 @@ def pk_and_sequence_for(table)
         execute_and_free("SHOW CREATE TABLE #{quote_table_name(table)}", 'SCHEMA') do |result|
           create_table = each_hash(result).first[:"Create Table"]
           if create_table.to_s =~ /PRIMARY KEY\s+\((.+)\)/
-            keys = $1.split(",").map { |key| key.gsub(/[`"]/, "") }
+            keys = $1.split(",").map { |key| key.delete('`"') }
             keys.length == 1 ? [keys.first, nil] : nil
           else
             nil