diff --git a/tools/cooja/java/se/sics/cooja/EventQueue.java b/tools/cooja/java/se/sics/cooja/EventQueue.java
index a7a725d05..24eb4b719 100644
--- a/tools/cooja/java/se/sics/cooja/EventQueue.java
+++ b/tools/cooja/java/se/sics/cooja/EventQueue.java
@@ -26,7 +26,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: EventQueue.java,v 1.9 2009/10/27 10:06:59 fros4943 Exp $
+ * $Id: EventQueue.java,v 1.10 2010/10/04 10:11:55 nifi Exp $
  */
 
 package se.sics.cooja;
@@ -51,11 +51,11 @@ public class EventQueue {
   }
 
   private void addEvent(TimeEvent event) {
-    if (event.removed && event.queue != null) {
-      removeFromQueue(event);
-    }
     if (event.queue != null) {
-      throw new IllegalStateException("Event was already scheduled in the past: " + event);
+      if (!event.isScheduled) {
+        removeFromQueue(event);
+      }
+      throw new IllegalStateException("Event is already scheduled: " + event);
     }
 
     if (first == null) {
@@ -78,8 +78,8 @@ public class EventQueue {
         lastPos.nextEvent = event;
       }
     }
-    event.removed = false;
     event.queue = this;
+    event.isScheduled = true;
     eventCount++;
   }
 
@@ -112,6 +112,7 @@ public class EventQueue {
     pos.nextEvent = null;
 
     event.queue = null;
+    event.isScheduled = false;
     eventCount--;
     return true;
   }
@@ -142,10 +143,11 @@ public class EventQueue {
     tmp.queue = null;
     eventCount--;
 
-    if (tmp.removed) {
+    if (!tmp.isScheduled) {
       /* pop and return another event instead */
       return popFirst();
     }
+    tmp.isScheduled = false;
     return tmp;
   }
 
diff --git a/tools/cooja/java/se/sics/cooja/Simulation.java b/tools/cooja/java/se/sics/cooja/Simulation.java
index 0b2305fe8..0f52fe781 100644
--- a/tools/cooja/java/se/sics/cooja/Simulation.java
+++ b/tools/cooja/java/se/sics/cooja/Simulation.java
@@ -24,7 +24,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- * $Id: Simulation.java,v 1.65 2010/08/13 09:53:33 fros4943 Exp $
+ * $Id: Simulation.java,v 1.66 2010/10/04 10:11:56 nifi Exp $
  */
 
 package se.sics.cooja;
@@ -180,12 +180,9 @@ public class Simulation extends Observable implements Runnable {
    * @param time Execution time
    */
   public void scheduleEvent(final TimeEvent e, final long time) {
-    /* TODO Strict scheduling from simulation thread */
-    if (e.isScheduled()) {
-      throw new IllegalStateException("Event already scheduled: " + e);
-    }
-    if (isRunning && !isSimulationThread()) {
-      throw new IllegalStateException("Scheduling event from non-simulation thread: " + e);
+    if (isRunning) {
+      /* TODO Strict scheduling from simulation thread */
+      assert isSimulationThread() : "Scheduling event from non-simulation thread: " + e;
     }
     eventQueue.addEvent(e, time);
   }
diff --git a/tools/cooja/java/se/sics/cooja/TimeEvent.java b/tools/cooja/java/se/sics/cooja/TimeEvent.java
index c96a69bbb..24388c580 100644
--- a/tools/cooja/java/se/sics/cooja/TimeEvent.java
+++ b/tools/cooja/java/se/sics/cooja/TimeEvent.java
@@ -26,7 +26,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: TimeEvent.java,v 1.4 2009/03/03 13:42:45 fros4943 Exp $
+ * $Id: TimeEvent.java,v 1.5 2010/10/04 10:11:55 nifi Exp $
  */
 
 package se.sics.cooja;
@@ -43,7 +43,7 @@ public abstract class TimeEvent {
 
   protected long time;
 
-  boolean removed = false;
+  boolean isScheduled = false;
 
   public TimeEvent(long time) {
     this(time, null);
@@ -59,11 +59,11 @@ public abstract class TimeEvent {
   }
 
   public boolean isScheduled() {
-    return queue != null && !removed;
+    return isScheduled;
   }
 
   public boolean remove() {
-    removed = true;
+    isScheduled = false;
     return false;
   }