diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index b5035cef6..ec2327199 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -2007,11 +2007,11 @@ void Mle::HandleUdpReceive(Message &aMessage, const Ip6::MessageInfo &aMessageIn
     uint8_t command;
     Neighbor *neighbor;
 
+    VerifyOrExit(aMessageInfo.GetLinkInfo() != NULL);
+
     length = aMessage.Read(aMessage.GetOffset(), sizeof(header), &header);
     VerifyOrExit(header.IsValid() && header.GetLength() <= length);
 
-    assert(aMessageInfo.GetLinkInfo() != NULL);
-
     if (header.GetSecuritySuite() == Header::kNoSecurity)
     {
         aMessage.MoveOffset(header.GetLength());