diff --git a/ChangeLog b/ChangeLog
index 561b3b6f45..7049eaa311 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,12 +1,15 @@
+Wed Apr  9 14:43:26 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* thread.c (lock_func): optimized and checks for interrupt_flag.
+	  based on a patch from Sylvain Joyeux in [ruby-Patches-19361] and
+	  [ruby-Patches-19362].
+
 Wed Apr  9 12:12:01 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* test/ruby/test_thread.rb: new tests from Sylvain Joyeux in
 	  [ruby-Patches-19361].
 
-Tue Apr  8 21:38:55 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
-
-	* thread.c (lock_func): optimized.  based on a patch from Sylvain
-	  Joyeux in [ruby-Patches-19362].
+Tue Apr  8 21:36:40 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* thread.c (rb_mutex_sleep): ensures to re-acquire at waking up.
 	  [ruby-Patches-19361]
diff --git a/thread.c b/thread.c
index 4f713a2cc9..57b2085735 100644
--- a/thread.c
+++ b/thread.c
@@ -2320,30 +2320,19 @@ rb_mutex_trylock(VALUE self)
 static VALUE
 lock_func(rb_thread_t *th, mutex_t *mutex)
 {
-    int locked = 0;
+    native_mutex_lock(&mutex->lock);
+    while (mutex->th) {
+	mutex->cond_waiting++;
+	native_cond_wait(&mutex->cond, &mutex->lock);
 
-    while (locked == 0) {
-	native_mutex_lock(&mutex->lock);
-	{
-	    if (mutex->th == 0) {
-		mutex->th = th;
-		locked = 1;
-	    }
-	    else {
-		mutex->cond_waiting++;
-		native_cond_wait(&mutex->cond, &mutex->lock);
-
-		if (th->interrupt_flag) {
-		    locked = 1;
-		}
-		else if (mutex->th == 0) {
-		    mutex->th = th;
-		    locked = 1;
-		}
-	    }
+	if (th->interrupt_flag) {
+	    native_mutex_unlock(&mutex->lock);
+	    RUBY_VM_CHECK_INTS();
+	    native_mutex_lock(&mutex->lock);
 	}
-	native_mutex_unlock(&mutex->lock);
     }
+    mutex->th = th;
+    native_mutex_unlock(&mutex->lock);
     return Qnil;
 }