diff --git a/rpc/api/miner.go b/rpc/api/miner.go
index 4cec1e79ce..5956d40fb7 100644
--- a/rpc/api/miner.go
+++ b/rpc/api/miner.go
@@ -126,6 +126,10 @@ func (self *minerApi) SetExtra(req *shared.Request) (interface{}, error) {
 		return nil, err
 	}
 
+	if common.IsHex(args.Data) {
+		args.Data = string(common.FromHex(args.Data)) //convert the byte array back to a string
+	}
+
 	if uint64(len(args.Data)) > params.MaximumExtraDataSize.Uint64() {
 		return false, fmt.Errorf("extra datasize can be no longer than %v bytes", params.MaximumExtraDataSize)
 	}