diff --git a/tools/cooja/apps/mspsim/src/se/sics/cooja/mspmote/interfaces/MspMoteID.java b/tools/cooja/apps/mspsim/src/se/sics/cooja/mspmote/interfaces/MspMoteID.java
index 137472936..2b1abcfac 100644
--- a/tools/cooja/apps/mspsim/src/se/sics/cooja/mspmote/interfaces/MspMoteID.java
+++ b/tools/cooja/apps/mspsim/src/se/sics/cooja/mspmote/interfaces/MspMoteID.java
@@ -84,19 +84,31 @@ public class MspMoteID extends MoteID {
 		moteID = newID;
 
 		/* Write node-unique infomem entry, used to configure node_id and node_mac */
-		if (mote.getMemory().getMemorySegment(0x1980, 10) != null) {
-			byte[] infomem = new byte[10];
-			infomem[0] = (byte) 0xab; /* magic */
-			infomem[1] = (byte) 0xcd; /* magic */
-			infomem[2] = (byte) 0x02;
-			infomem[3] = (byte) 0x12;
-			infomem[4] = (byte) 0x74;
-			infomem[5] = (byte) 0x00;
-			infomem[6] = (byte) 0x00;
-			infomem[7] = (byte) 0x01;
-			infomem[8] = (byte) ((newID << 8) & 0xFF);
-                        infomem[9] = (byte) (newID & 0xFF);
-			mote.getMemory().setMemorySegment(0x1980, infomem);
+		byte[] infomemCurrent = mote.getMemory().getMemorySegment(0x1980, 10);
+		if (infomemCurrent != null) {
+			/* Only write to infomem is nothing else resides there */
+			boolean ffOnly = true;
+			for (byte b: infomemCurrent) {
+				if (b != (byte) 0xff) {
+					ffOnly = false;
+					break;
+				}
+			}
+
+			if (ffOnly) {
+				byte[] infomem = new byte[10];
+				infomem[0] = (byte) 0xab; /* magic */
+				infomem[1] = (byte) 0xcd; /* magic */
+				infomem[2] = (byte) 0x02;
+				infomem[3] = (byte) 0x12;
+				infomem[4] = (byte) 0x74;
+				infomem[5] = (byte) 0x00;
+				infomem[6] = (byte) 0x00;
+				infomem[7] = (byte) 0x01;
+				infomem[8] = (byte) ((newID << 8) & 0xFF);
+				infomem[9] = (byte) (newID & 0xFF);
+				mote.getMemory().setMemorySegment(0x1980, infomem);
+			}
 		}
 		
 		if (moteMem.variableExists("node_id")) {