diff --git a/prelude.rb b/prelude.rb
index 04bf850..2dca179 100644
--- a/prelude.rb
+++ b/prelude.rb
@@ -1,19 +1,3 @@
-class Mutex
-  # call-seq:
-  #    mutex.synchronize { ... }
-  #
-  # Obtains a lock, runs the block, and releases the lock when the
-  # block completes.  See the example under Mutex.
-  def synchronize
-    self.lock
-    begin
-      yield
-    ensure
-      self.unlock rescue nil
-    end
-  end
-end
-
 class Thread
   MUTEX_FOR_THREAD_EXCLUSIVE = Mutex.new # :nodoc:
 
diff --git a/thread.c b/thread.c
index 69fc299..e6a2e8b 100644
--- a/thread.c
+++ b/thread.c
@@ -3435,6 +3435,12 @@ rb_mutex_synchronize(VALUE mutex, VALUE (*func)(VALUE arg), VALUE arg)
     return rb_ensure(func, arg, rb_mutex_unlock, mutex);
 }
 
+static VALUE
+rb_synchronize(VALUE self)
+{
+    return rb_mutex_synchronize(self, rb_yield, Qnil);
+}
+
 /*
  * Document-class: Barrier
  */
@@ -4381,6 +4387,7 @@ Init_Thread(void)
     rb_define_method(rb_cMutex, "lock", rb_mutex_lock, 0);
     rb_define_method(rb_cMutex, "unlock", rb_mutex_unlock, 0);
     rb_define_method(rb_cMutex, "sleep", mutex_sleep, -1);
+    rb_define_method(rb_cMutex, "synchronize", rb_synchronize, 0);
 
     recursive_key = rb_intern("__recursive_key__");
     rb_eThreadError = rb_define_class("ThreadError", rb_eStandardError);