diff --git a/src/unix/unix_thread.c b/src/unix/unix_thread.c
index dc7625e12..5221d90eb 100644
--- a/src/unix/unix_thread.c
+++ b/src/unix/unix_thread.c
@@ -157,6 +157,18 @@ thread_wait_mutex(mutex_t *_mutex)
 }
 
 
+int
+thread_test_mutex(mutex_t *_mutex)
+{
+    if (_mutex == NULL)
+	return(0);
+    pt_mutex_t *mutex = (pt_mutex_t *)_mutex;
+
+    return
+	pthread_mutex_trylock(&mutex->mutex) != 0;
+}
+
+
 int
 thread_release_mutex(mutex_t *_mutex)
 {