diff --git a/u05-4/WorkQueue.java b/u05-4/WorkQueue.java
index 0f37af7..3377f72 100644
--- a/u05-4/WorkQueue.java
+++ b/u05-4/WorkQueue.java
@@ -4,22 +4,26 @@ import java.util.Queue;
 import java.util.concurrent.Semaphore;
 
 class WorkQueue {
-	private Queue<Task> tasks = new LinkedList<Task>();
+	private volatile Queue<Task> tasks = new LinkedList<Task>();
 	private Semaphore readSemaphore;
 	private Semaphore writeSemaphore;
+	private Semaphore generalAccessSemaphore;
 
 	public WorkQueue(int maxSize) {
 		readSemaphore = new Semaphore(0);
 		writeSemaphore = new Semaphore(maxSize);
+		generalAccessSemaphore = new Semaphore(1);
 	}
 
 	public void producer() throws InterruptedException {
 		writeSemaphore.acquire();
+		generalAccessSemaphore.acquire();
 
 		Task t = new Task();
 		tasks.add(t);
 
 		readSemaphore.release();
+		generalAccessSemaphore.release();
 	}
 
 	public void consumer() throws InterruptedException {
@@ -27,9 +31,10 @@ class WorkQueue {
 		Task t;
 
 		readSemaphore.acquire();
+		generalAccessSemaphore.acquire();
 
 		// for some reason, consumer can get here without tasks in the list. how to fix?
-		System.out.println(tasks.size());
+		// -> adding general access semaphore fixed it :)
 		if (tasks.isEmpty()) {
 			// SHOULD never be reached
 			System.out.println("!!! No tasks in the queue");
@@ -43,6 +48,7 @@ class WorkQueue {
 		}
 
 		writeSemaphore.release();
+		generalAccessSemaphore.release();
 
 		t.run();
 	}
@@ -54,17 +60,15 @@ class WorkQueue {
 
 	public static void main(String[] args) {
 		WorkQueue w = new WorkQueue(10);
-		Thread[] producers = new Thread[5];
-		Thread[] consumers = new Thread[5];
-		for (int i = 1; i <= 2; i++) {
-			final int i_final = i;
+		Thread[] producers = new Thread[50];
+		Thread[] consumers = new Thread[50];
+		for (int i = 0; i < 50; i++) {
 			producers[i] = new Thread(() -> {
 				try {
-					for (int j = 0; j < 10; j++) {
+					for (int j = 0; j < 100; j++) {
 						w.producer();
-						System.out.println("Producer " + i_final + " produced task " + j);
 						w.printTaksSize();
-						// Thread.sleep(100);
+						Thread.sleep(100);
 					}
 				} catch (InterruptedException e) {
 					Thread.currentThread().interrupt();
@@ -72,11 +76,10 @@ class WorkQueue {
 			});
 			consumers[i] = new Thread(() -> {
 				try {
-					for (int j = 0; j < 10; j++) {
+					for (int j = 0; j < 100; j++) {
 						w.consumer();
 						w.printTaksSize();
-						System.out.println("Consumer " + i_final + " consumed task " + j);
-						// Thread.sleep(100);
+						Thread.sleep(100);
 					}
 				} catch (InterruptedException e) {
 					Thread.currentThread().interrupt();