diff --git a/ChangeLog b/ChangeLog
index e8b3838ddb..9f786630fe 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+Sat Jun 13 07:21:18 2015  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* thread.c (thread_start_func_2): don't interrupt when last thread
+	  exit unless main thread is already exited. Otherwise main thread
+	  could be wrongly interrupted when it uses rb_thread_call_without_gvl().
+	  Patch by Takehiro Kubo. [Bug #11237][ruby-dev:49044][GH-898]
+
+	* test/-ext-/gvl/test_last_thread.rb: new test for the above fix.
+
+	* ext/-test-/gvl/call_without_gvl/call_without_gvl.c: new ext for
+	  the above test.
+	* ext/-test-/gvl/call_without_gvl/extconf.rb: ditto.
+
 Mon Jun 15 00:14:33 2015  Tanaka Akira  <akr@fsij.org>
 
 	* ext/pathname/lib/pathname.rb (descend): Blockless form supported.
diff --git a/ext/-test-/gvl/call_without_gvl/call_without_gvl.c b/ext/-test-/gvl/call_without_gvl/call_without_gvl.c
new file mode 100644
index 0000000000..0ee64a24ac
--- /dev/null
+++ b/ext/-test-/gvl/call_without_gvl/call_without_gvl.c
@@ -0,0 +1,35 @@
+#include "ruby/ruby.h"
+#include "ruby/thread.h"
+#include <sys/select.h>
+
+static void*
+native_sleep_callback(void *data)
+{
+    struct timeval *timeval = data;
+    select(0, NULL, NULL, NULL, timeval);
+
+    return NULL;
+}
+
+
+static VALUE
+thread_runnable_sleep(VALUE thread, VALUE timeout)
+{
+    struct timeval timeval;
+
+    if (NIL_P(timeout)) {
+	rb_raise(rb_eArgError, "timeout must be non nil");
+    }
+
+    timeval = rb_time_interval(timeout);
+
+    rb_thread_call_without_gvl(native_sleep_callback, &timeval, RUBY_UBF_IO, NULL);
+
+    return thread;
+}
+
+void
+Init_call_without_gvl(void)
+{
+    rb_define_method(rb_cThread, "__runnable_sleep__", thread_runnable_sleep, 1);
+}
diff --git a/ext/-test-/gvl/call_without_gvl/extconf.rb b/ext/-test-/gvl/call_without_gvl/extconf.rb
new file mode 100644
index 0000000000..601944c9e5
--- /dev/null
+++ b/ext/-test-/gvl/call_without_gvl/extconf.rb
@@ -0,0 +1 @@
+create_makefile("-test-/gvl/call_without_gvl")
diff --git a/test/-ext-/gvl/test_last_thread.rb b/test/-ext-/gvl/test_last_thread.rb
new file mode 100644
index 0000000000..df25165b4b
--- /dev/null
+++ b/test/-ext-/gvl/test_last_thread.rb
@@ -0,0 +1,22 @@
+class TestLastThread < Test::Unit::TestCase
+
+  # [Bug #11237]
+  def test_last_thread
+
+    assert_separately([], <<-"end;") #do
+      require '-test-/gvl/call_without_gvl'
+
+      Thread.new {
+        sleep 0.2
+      }
+
+      t0 = Time.now
+      Thread.current.__runnable_sleep__ 1
+      t1 = Time.now
+      t = t1 - t0
+
+      assert_operator(t, :>=, 1)
+    end;
+  end
+end
+
diff --git a/thread.c b/thread.c
index bf045a44ea..8e8d8fbdfe 100644
--- a/thread.c
+++ b/thread.c
@@ -629,7 +629,7 @@ thread_start_func_2(rb_thread_t *th, VALUE *stack_start, VALUE *register_stack_s
 
 	/* delete self other than main thread from living_threads */
 	rb_vm_living_threads_remove(th->vm, th);
-	if (rb_thread_alone()) {
+	if (main_th->status == THREAD_KILLED && rb_thread_alone()) {
 	    /* I'm last thread. wake up main thread from rb_thread_terminate_all */
 	    rb_threadptr_interrupt(main_th);
 	}