1 files changed, 6 insertions, 1 deletions
diff --git a/thread.c b/thread.c
index ae4e669d15..8547ff8738 100644
--- a/thread.c
+++ b/thread.c
@@ -3235,10 +3235,15 @@ lock_func(rb_thread_t *th, mutex_t *mutex, int timeout_ms)
 
     native_mutex_lock(&mutex->lock);
     th->transition_for_lock = 0;
-    while (mutex->th || (mutex->th = th, 0)) {
+    for (;;) {
 	struct timespec ts;
 	int ret;
 
+	if (!mutex->th) {
+	    mutex->th = th;
+	    break;
+	}
+
 	mutex->cond_waiting++;
 	if (timeout_ms) {
 	    ts = init_lock_timeout(timeout_ms);