diff --git a/lib/libc_r/uthread/uthread_mutex.c b/lib/libc_r/uthread/uthread_mutex.c
index f7662c71c951..ec6c0f6f4e6a 100644
--- a/lib/libc_r/uthread/uthread_mutex.c
+++ b/lib/libc_r/uthread/uthread_mutex.c
@@ -402,6 +402,9 @@ pthread_mutex_lock(pthread_mutex_t * mutex)
 {
 	int	ret = 0;
 
+	if (_thread_initial == NULL)
+		_thread_init();
+
 	if (mutex == NULL)
 		ret = EINVAL;
 
diff --git a/lib/libkse/thread/thr_mutex.c b/lib/libkse/thread/thr_mutex.c
index f7662c71c951..ec6c0f6f4e6a 100644
--- a/lib/libkse/thread/thr_mutex.c
+++ b/lib/libkse/thread/thr_mutex.c
@@ -402,6 +402,9 @@ pthread_mutex_lock(pthread_mutex_t * mutex)
 {
 	int	ret = 0;
 
+	if (_thread_initial == NULL)
+		_thread_init();
+
 	if (mutex == NULL)
 		ret = EINVAL;
 
diff --git a/lib/libpthread/thread/thr_mutex.c b/lib/libpthread/thread/thr_mutex.c
index f7662c71c951..ec6c0f6f4e6a 100644
--- a/lib/libpthread/thread/thr_mutex.c
+++ b/lib/libpthread/thread/thr_mutex.c
@@ -402,6 +402,9 @@ pthread_mutex_lock(pthread_mutex_t * mutex)
 {
 	int	ret = 0;
 
+	if (_thread_initial == NULL)
+		_thread_init();
+
 	if (mutex == NULL)
 		ret = EINVAL;