diff --git a/lib/active_record/connection_adapters/oracle_enhanced/jdbc_connection.rb b/lib/active_record/connection_adapters/oracle_enhanced/jdbc_connection.rb
index 3f227a5af..a65a4d815 100644
--- a/lib/active_record/connection_adapters/oracle_enhanced/jdbc_connection.rb
+++ b/lib/active_record/connection_adapters/oracle_enhanced/jdbc_connection.rb
@@ -98,6 +98,8 @@ def new_connection(config)
               @raw_connection = @raw_connection.underlying_connection
             end
 
+            # Workaround FrozenError (can't modify frozen Hash):
+            config = config.dup
             config[:driver] ||= @raw_connection.meta_data.connection.java_class.name
             username = @raw_connection.meta_data.user_name
           else
diff --git a/lib/active_record/connection_adapters/oracle_enhanced/quoting.rb b/lib/active_record/connection_adapters/oracle_enhanced/quoting.rb
index 5907a266e..a4d2c420f 100644
--- a/lib/active_record/connection_adapters/oracle_enhanced/quoting.rb
+++ b/lib/active_record/connection_adapters/oracle_enhanced/quoting.rb
@@ -10,14 +10,11 @@ module Quoting
 
         def quote_column_name(name) #:nodoc:
           name = name.to_s
-          self.class.quoted_column_names[name] ||= begin
-            # if only valid lowercase column characters in name
-            if /\A[a-z][a-z_0-9\$#]*\Z/.match?(name)
-              "\"#{name.upcase}\""
-            else
-              # remove double quotes which cannot be used inside quoted identifier
-              "\"#{name.gsub('"', '')}\""
-            end
+          self.class.quoted_column_names[name] ||= if /\A[a-z][a-z_0-9\$#]*\Z/.match?(name)
+            "\"#{name.upcase}\""
+          else
+            # remove double quotes which cannot be used inside quoted identifier
+            "\"#{name.gsub('"', '')}\""
           end
         end