diff --git a/scapy/layers/dhcp.py b/scapy/layers/dhcp.py
index 18f83f00da6e7f05b118ec4cf4a68cf19e6cf17d..c5bab7ee48bcaafa60c3225e9608a954cf7066d7 100644
--- a/scapy/layers/dhcp.py
+++ b/scapy/layers/dhcp.py
@@ -116,6 +116,7 @@ DHCPOptions = {
     51: IntField("lease_time", 43200),
     54: IPField("server_id","0.0.0.0"),
     55: "param_req_list",
+    56: StrField("error_message", ""),
     57: ShortField("max_dhcp_size", 1500),
     58: IntField("renewal_time", 21600),
     59: IntField("rebinding_time", 37800),