diff --git a/tools/cooja/java/se/sics/cooja/contikimote/interfaces/ContikiRS232.java b/tools/cooja/java/se/sics/cooja/contikimote/interfaces/ContikiRS232.java
index c55160491..b39292dec 100644
--- a/tools/cooja/java/se/sics/cooja/contikimote/interfaces/ContikiRS232.java
+++ b/tools/cooja/java/se/sics/cooja/contikimote/interfaces/ContikiRS232.java
@@ -70,6 +70,8 @@ public class ContikiRS232 extends SerialUI implements ContikiMoteInterface, Poll
   private ContikiMote mote = null;
   private SectionMoteMemory moteMem = null;
 
+  static final int SERIAL_BUF_SIZE = 1024; /* rs232.c:40 */
+  
   /**
    * Creates an interface to the RS232 at mote.
    *
@@ -109,6 +111,11 @@ public class ContikiRS232 extends SerialUI implements ContikiMoteInterface, Poll
         /* Append to existing buffer */
         int oldSize = moteMem.getIntValueOf("simSerialReceivingLength");
         int newSize = oldSize + dataToAppend.length;
+        if (newSize > SERIAL_BUF_SIZE) {
+        	logger.fatal("ContikiRS232: dropping rs232 data #1, buffer full: " + oldSize + " -> " + newSize);
+        	mote.requestImmediateWakeup();
+        	return;
+        }
         moteMem.setIntValueOf("simSerialReceivingLength", newSize);
 
         byte[] oldData = moteMem.getByteArray("simSerialReceivingData", oldSize);
@@ -159,6 +166,11 @@ public class ContikiRS232 extends SerialUI implements ContikiMoteInterface, Poll
         /* Append to existing buffer */
         int oldSize = moteMem.getIntValueOf("simSerialReceivingLength");
         int newSize = oldSize + dataToAppend.length;
+        if (newSize > SERIAL_BUF_SIZE) {
+        	logger.fatal("ContikiRS232: dropping rs232 data #2, buffer full: " + oldSize + " -> " + newSize);
+        	mote.requestImmediateWakeup();
+        	return;
+        }
         moteMem.setIntValueOf("simSerialReceivingLength", newSize);
 
         byte[] oldData = moteMem.getByteArray("simSerialReceivingData", oldSize);
@@ -212,6 +224,11 @@ public class ContikiRS232 extends SerialUI implements ContikiMoteInterface, Poll
         /* Append to existing buffer */
         int oldSize = moteMem.getIntValueOf("simSerialReceivingLength");
         int newSize = oldSize + dataToAppend.length;
+        if (newSize > SERIAL_BUF_SIZE) {
+        	logger.fatal("ContikiRS232: dropping rs232 data #3, buffer full: " + oldSize + " -> " + newSize);
+        	mote.requestImmediateWakeup();
+        	return;
+        }
         moteMem.setIntValueOf("simSerialReceivingLength", newSize);
 
         byte[] oldData = moteMem.getByteArray("simSerialReceivingData", oldSize);
@@ -229,13 +246,26 @@ public class ContikiRS232 extends SerialUI implements ContikiMoteInterface, Poll
         mote.requestImmediateWakeup();
       }
     };
+
+    /* Simulation thread: schedule immediately */
+    if (mote.getSimulation().isSimulationThread()) {
+    	mote.getSimulation().scheduleEvent(
+    			pendingBytesEvent,
+    			mote.getSimulation().getSimulationTime()
+    			);
+    	return;
+    }
+
     mote.getSimulation().invokeSimulationThread(new Runnable() {
-      public void run() {
-        mote.getSimulation().scheduleEvent(
-            pendingBytesEvent,
-            mote.getSimulation().getSimulationTime()
-        );
-      }
+    	public void run() {
+    		if (pendingBytesEvent.isScheduled()) {
+    			return;
+    		}
+    		mote.getSimulation().scheduleEvent(
+    				pendingBytesEvent,
+    				mote.getSimulation().getSimulationTime()
+    				);
+    	}
     });
   }