diff --git a/arcadia/arcadia.go b/arcadia/arcadia.go
index 7bcfa55859..0175031a06 100644
--- a/arcadia/arcadia.go
+++ b/arcadia/arcadia.go
@@ -585,17 +585,30 @@ func (cli *Arcadia) GetBlockPayloadFromArcadia(ctx context.Context, maxBw, block
 		MaxBandwidth: maxBw,
 		BlockNumber:  blockNumber,
 	}
-	reqRaw, err := json.Marshal(reqr)
+	reqRaw, err := reqr.Payload()
 	if err != nil {
 		return nil, err
 	}
 
+	uwm, err := warp.NewUnsignedMessage(cli.vm.NetworkID(), cli.vm.ChainID(), reqRaw)
+	if err != nil {
+		return nil, err
+	}
+	sig, err := cli.vm.Sign(uwm)
+	if err != nil {
+		return nil, err
+	}
+	sigStr := hexutil.Encode(sig)
+
+	cli.vm.Logger().Debug("signing GetArcadiaBlock request with", zap.String("pubkey", hexutil.Encode(cli.vm.Signer().Compress())), zap.Uint64("height", blockNumber), zap.String("chainID", cli.vm.ChainID().String()), zap.Uint32("networkID", cli.vm.NetworkID()))
+
 	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewBuffer(reqRaw))
 	if err != nil {
 		return nil, err
 	}
 
 	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set(GetArcadiaBlockSignatureHeader, sigStr)
 
 	resp, err := client.Do(req)
 	if err != nil {
diff --git a/arcadia/consts.go b/arcadia/consts.go
index 052bddaa01..c3c5b4ff89 100644
--- a/arcadia/consts.go
+++ b/arcadia/consts.go
@@ -3,3 +3,4 @@ package arcadia
 var DefaultNMTNamespace = make([]byte, 8)
 
 const DefaultBuilderLRUSize = 20
+const GetArcadiaBlockSignatureHeader = "X-Arcadia-GetBlock-Sig"
diff --git a/arcadia/types.go b/arcadia/types.go
index 1fed2901a6..eccc5b97f9 100644
--- a/arcadia/types.go
+++ b/arcadia/types.go
@@ -1,6 +1,8 @@
 package arcadia
 
 import (
+	"encoding/json"
+
 	"github.com/ava-labs/avalanchego/ids"
 	"github.com/bits-and-blooms/bitset"
 
@@ -69,6 +71,10 @@ type GetBlockPayloadFromArcadia struct {
 	BlockNumber  uint64 `json:"blockNumber"`
 }
 
+func (req *GetBlockPayloadFromArcadia) Payload() ([]byte, error) {
+	return json.Marshal(req)
+}
+
 type ChunkInterface interface {
 	Marshal() ([]byte, error)
 	Transactions() []*chain.Transaction
diff --git a/arcadia/utils.go b/arcadia/utils.go
index 124a505242..f5fc5c4615 100644
--- a/arcadia/utils.go
+++ b/arcadia/utils.go
@@ -97,7 +97,9 @@ func replaceHTTPWithWS(url string) string {
 }
 
 func namespaceToChainIDStr(ns []byte) string {
-	chainIDu64 := binary.LittleEndian.Uint64(ns)
+	nsPadded := make([]byte, 8)
+	copy(nsPadded[:], ns)
+	chainIDu64 := binary.LittleEndian.Uint64(nsPadded)
 	chainID := big.NewInt(int64(chainIDu64))
 
 	return hexutil.EncodeBig(chainID)