diff --git a/src/thread/pthread_mutex_lock.c b/src/thread/pthread_mutex_lock.c
index 87b19752ee0e4d2845a9e430ae2b60447c4533a4..99c15bd8f6f649c79f61c807341d049b878a3396 100644
--- a/src/thread/pthread_mutex_lock.c
+++ b/src/thread/pthread_mutex_lock.c
@@ -4,7 +4,7 @@ int pthread_mutex_lock(pthread_mutex_t *m)
 {
 	int r;
 
-	if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_swap(&m->_m_lock, 1))
+	if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_swap(&m->_m_lock, EBUSY))
 		return 0;
 
 	while ((r=pthread_mutex_trylock(m)) == EBUSY) {
diff --git a/src/thread/pthread_mutex_trylock.c b/src/thread/pthread_mutex_trylock.c
index 50a815a5fbf4dc22322347fa2ab4aaaeb98348b2..ea1fa80527698d9a20cad0c616f0971d50bdbb1c 100644
--- a/src/thread/pthread_mutex_trylock.c
+++ b/src/thread/pthread_mutex_trylock.c
@@ -7,7 +7,7 @@ int pthread_mutex_trylock(pthread_mutex_t *m)
 	pthread_t self;
 
 	if (m->_m_type == PTHREAD_MUTEX_NORMAL)
-		return -a_swap(&m->_m_lock, 1) & EBUSY;
+		return a_swap(&m->_m_lock, EBUSY);
 
 	self = pthread_self();
 	tid = self->tid | 0x80000000;