diff --git a/se/sics/mspsim/chip/CC2420.java b/se/sics/mspsim/chip/CC2420.java
index 427bfc4..1118cf1 100644
--- a/se/sics/mspsim/chip/CC2420.java
+++ b/se/sics/mspsim/chip/CC2420.java
@@ -680,6 +680,12 @@ public class CC2420 extends Chip implements USARTListener, RFListener, RFSource
           autoCRC = (data & ADR_AUTOCRC) != 0;
           autoAck = (data & AUTOACK) != 0;
           break;
+      case REG_FSCTRL:
+      	if (cl != null) {
+      		updateActiveFrequency();
+      		cl.changedChannel(activeChannel);
+      	}
+        break;
       }
   }
     
@@ -1223,6 +1229,14 @@ public class CC2420 extends Chip implements USARTListener, RFListener, RFSource
     listener = rf;
   }
 
+  public interface ChannelListener {
+    public void changedChannel(int channel);
+  }
+  private ChannelListener cl = null;
+  public void setChannelListener(ChannelListener cl) {
+    this.cl = cl;
+  }
+
   public void setVRegOn(boolean newOn) {
     if(on == newOn) return;