diff --git a/tools/cooja/java/org/contikios/cooja/plugins/analyzers/PacketAnalyzer.java b/tools/cooja/java/org/contikios/cooja/plugins/analyzers/PacketAnalyzer.java
index 3be8a8284..7f4002960 100644
--- a/tools/cooja/java/org/contikios/cooja/plugins/analyzers/PacketAnalyzer.java
+++ b/tools/cooja/java/org/contikios/cooja/plugins/analyzers/PacketAnalyzer.java
@@ -55,7 +55,7 @@ public abstract class PacketAnalyzer {
     public int getInt(int index, int size) {
       int value = 0;
       for (int i = 0; i < size; i++) {
-        value = (value << 8) + get(index + i);
+        value = (value << 8) + (get(index + i) & 0xFF);
       }
       return value;
     }