diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index 66302aa38..06433ce32 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -2882,7 +2882,10 @@ void MleRouter::HandleDataRequest(RxInfo &aRxInfo)
         OT_FALL_THROUGH;
 
     case kErrorNotFound:
-        tlvs[numTlvs++] = Tlv::kActiveDataset;
+        if (numTlvs < sizeof(tlvs))
+        {
+            tlvs[numTlvs++] = Tlv::kActiveDataset;
+        }
         break;
 
     default:
@@ -2901,7 +2904,10 @@ void MleRouter::HandleDataRequest(RxInfo &aRxInfo)
         OT_FALL_THROUGH;
 
     case kErrorNotFound:
-        tlvs[numTlvs++] = Tlv::kPendingDataset;
+        if (numTlvs < sizeof(tlvs))
+        {
+            tlvs[numTlvs++] = Tlv::kPendingDataset;
+        }
         break;
 
     default: