diff --git a/ChangeLog b/ChangeLog
index f856ed6601..9323ed5ae5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Sat Feb 22 13:17:32 2014  Masaki Matsushita  <glass.saga@gmail.com>
+
+	* ext/thread/thread.c (rb_szqueue_clear): notify SZQUEUE_WAITERS
+	  on SizedQueue#clear. [ruby-core:59462] [Bug #9342]
+
+	* test/thread/test_queue.rb: add test. the patch is from
+	  Justin Collins.
+
 Sat Feb 22 01:35:02 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in: check if pthread_setname_np is available.
diff --git a/ext/thread/thread.c b/ext/thread/thread.c
index a8f675c55b..c409b36da2 100644
--- a/ext/thread/thread.c
+++ b/ext/thread/thread.c
@@ -502,6 +502,20 @@ rb_szqueue_pop(int argc, VALUE *argv, VALUE self)
     return szqueue_do_pop(self, should_block);
 }
 
+/*
+ * Document-method: Queue#clear
+ *
+ * Removes all objects from the queue.
+ */
+
+static VALUE
+rb_szqueue_clear(VALUE self)
+{
+    rb_ary_clear(GET_QUEUE_QUE(self));
+    wakeup_all_threads(GET_SZQUEUE_WAITERS(self));
+    return self;
+}
+
 /*
  * Document-method: SizedQueue#num_waiting
  *
@@ -586,6 +600,7 @@ Init_thread(void)
     rb_define_method(rb_cSizedQueue, "max=", rb_szqueue_max_set, 1);
     rb_define_method(rb_cSizedQueue, "push", rb_szqueue_push, 1);
     rb_define_method(rb_cSizedQueue, "pop", rb_szqueue_pop, -1);
+    rb_define_method(rb_cSizedQueue, "clear", rb_szqueue_clear, 0);
     rb_define_method(rb_cSizedQueue, "num_waiting", rb_szqueue_num_waiting, 0);
 
     /* Alias for #push. */
diff --git a/test/thread/test_queue.rb b/test/thread/test_queue.rb
index 2126500bd8..c99475d8dc 100644
--- a/test/thread/test_queue.rb
+++ b/test/thread/test_queue.rb
@@ -129,6 +129,28 @@ class TestQueue < Test::Unit::TestCase
     assert_same q, retval
   end
 
+  def test_sized_queue_clear
+    # Fill queue, then test that SizedQueue#clear wakes up all waiting threads
+    sq = SizedQueue.new(2)
+    2.times { sq << 1 }
+
+    t1 = Thread.new do
+      sq << 1
+    end
+
+    t2 = Thread.new do
+      sq << 1
+    end
+
+    t3 = Thread.new do
+      Thread.pass
+      sq.clear
+    end
+
+    [t3, t2, t1].each(&:join)
+    assert_equal sq.length, 2
+  end
+
   def test_sized_queue_push_return_value
     q = SizedQueue.new(1)
     retval = q.push(1)
diff --git a/version.h b/version.h
index e352ebc6bf..2bb33993f5 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.1.1"
 #define RUBY_RELEASE_DATE "2014-02-22"
-#define RUBY_PATCHLEVEL 50
+#define RUBY_PATCHLEVEL 51
 
 #define RUBY_RELEASE_YEAR 2014
 #define RUBY_RELEASE_MONTH 2