diff --git a/src/exploit.cpp b/src/exploit.cpp
index 63e7cb9..669b255 100644
--- a/src/exploit.cpp
+++ b/src/exploit.cpp
@@ -1008,7 +1008,7 @@ int Exploit::stage4() {
 
         // last fragment
         if (offset + payloadSize >= this->stage2_bin.size()) {
-            ipLayer.getIPv4Header()->fragmentOffset = htobe16(offset / 8 + (offset != 0)) & 0xFF1F;
+            ipLayer.getIPv4Header()->fragmentOffset = htobe16(offset / 8 + (offset != 0)) & htobe16(0x1FFF);
             payloadSize = this->stage2_bin.size() - offset;
         }