diff --git a/activesupport/lib/active_support/core_ext/module/method_names.rb b/activesupport/lib/active_support/core_ext/module/method_names.rb
index 2eb40a83abc7472054d62195abf5c8f7e1795f2d..72d7091eb109d0a7aa44cf50502104a778d0abb0 100644
--- a/activesupport/lib/active_support/core_ext/module/method_names.rb
+++ b/activesupport/lib/active_support/core_ext/module/method_names.rb
@@ -1,14 +1,9 @@
 class Module
-  if instance_methods[0].is_a?(Symbol)
-    def instance_method_names(*args)
-      instance_methods(*args).map(&:to_s)
-    end
+  def instance_method_names(*args)
+    instance_methods(*args).map { |name| name.to_s }
+  end
 
-    def method_names(*args)
-      methods(*args).map(&:to_s)
-    end
-  else
-    alias_method :instance_method_names, :instance_methods
-    alias_method :method_names, :methods
+  def method_names(*args)
+    methods(*args).map { |name| name.to_s }
   end
-end
\ No newline at end of file
+end