diff --git a/ipc/sem.c b/ipc/sem.c
index 4a92c04..e20658d 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -257,12 +257,20 @@
  * Caller must own sem_perm.lock.
  * New simple ops cannot start, because simple ops first check
  * that sem_perm.lock is free.
+ * that a) sem_perm.lock is free and b) complex_count is 0.
  */
 static void sem_wait_array(struct sem_array *sma)
 {
 	int i;
 	struct sem *sem;
 
+	if (sma->complex_count)  {
+		/* The thread that increased sma->complex_count waited on
+		 * all sem->lock locks. Thus we don't need to wait again.
+		 */
+		return;
+	}
+
 	for (i = 0; i < sma->sem_nsems; i++) {
 		sem = sma->sem_base + i;
 		spin_unlock_wait(&sem->lock);