diff --git a/05-JurrasicPark/README.md b/05-JurrasicPark/README.md
index 012eb9c..6ea6f58 100644
--- a/05-JurrasicPark/README.md
+++ b/05-JurrasicPark/README.md
@@ -110,7 +110,7 @@ sem_t mySemaphore;
 pthread_mutex_lock(&mailboxMutex); // wait for mailbox
 sem_wait(&needPassenger); // wait for passenger request
 gMailbox = mySemaphore; // put semaphore in mailbox
-sem_post(vmailboxReady); // raise the mailbox flag
+sem_post(&mailboxReady); // raise the mailbox flag
 sem_wait(&mailAcquired); // wait for delivery
 pthread_mutex_unlock(&mailboxMutex); // release mailbox
 
@@ -120,10 +120,10 @@ sem_t passengerSems[3];
 //...
 
 // get passenger semaphore
-sem_post(needPassenger);
-sem_wait(mailboxReady); // wait for mail
+sem_post(&needPassenger);
+sem_wait(&mailboxReady); // wait for mail
 passengerSems[i] = gMailbox; // get mail
-sem_post(mailAcquired); // put flag down
+sem_post(&mailAcquired); // put flag down
 ```
 
 # Interfacing with "jurassicTask"