Index: pydhcplib/dhcp_basic_packet.py
===================================================================
--- python-pydhcplib/pydhcplib/dhcp_basic_packet.py
+++ python-pydhcplib/pydhcplib/dhcp_basic_packet.py
@@ -99,9 +99,9 @@
                              "char":[1,0,1], "16-bits":[2,0,1],
                              "32-bits":[4,0,1], "identifier":[0,2,1]}
             
-            specs = fields_specs[DhcpOptionsTypes[DhcpOptions[name]]]
+            specs = fields_specs.get(DhcpOptionsTypes[DhcpOptions[name]], [])
             length = len(value)
-            if (specs[0]!=0 and specs==length) or (specs[1]<=length and length%specs[2]==0):
+            if specs == [] or (specs[0]!=0 and specs==length) or (specs[1]<=length and length%specs[2]==0):
                 self.options_data[name] = value
                 return True
             else :
