diff --git a/src/core/thread/mle_ftd.cpp b/src/core/thread/mle_ftd.cpp
index 4fe922518..1686b30aa 100644
--- a/src/core/thread/mle_ftd.cpp
+++ b/src/core/thread/mle_ftd.cpp
@@ -2355,7 +2355,7 @@ void Mle::HandleChildUpdateRequestOnParent(RxInfo &aRxInfo)
         case kErrorNotFound:
             break;
         default:
-            ExitNow(error = kErrorNone);
+            ExitNow(error = kErrorParse);
         }
 
         switch (Tlv::Find<CslChannelTlv>(aRxInfo.mMessage, cslChannelTlvValue))