diff --git a/tools/cooja/apps/mrm/java/se/sics/mrm/MRM.java b/tools/cooja/apps/mrm/java/se/sics/mrm/MRM.java
index 383562221..ba9e45d0a 100644
--- a/tools/cooja/apps/mrm/java/se/sics/mrm/MRM.java
+++ b/tools/cooja/apps/mrm/java/se/sics/mrm/MRM.java
@@ -383,10 +383,16 @@ public class MRM extends AbstractRadioMedium {
     }
 
     public double getDestinationSignalStrength(Radio radio) {
+    	if (signalStrengths.get(radio) == null) {
+    		return Double.MIN_VALUE;
+    	}
       return signalStrengths.get(radio);
     }
 
     public double getInterferenceSignalStrength(Radio radio) {
+    	if (signalStrengths.get(radio) == null) {
+    		return Double.MIN_VALUE;
+    	}
       return signalStrengths.get(radio);
     }
   }