openflow_input: add inheritance
diff --git a/openflow_input/nicira_dec_ttl b/openflow_input/nicira_dec_ttl
index 77649af..3b95366 100644
--- a/openflow_input/nicira_dec_ttl
+++ b/openflow_input/nicira_dec_ttl
@@ -27,7 +27,7 @@
 
 #version any
 
-struct of_action_nicira_dec_ttl {
+struct of_action_nicira_dec_ttl : of_action_nicira {
     uint16_t type == 65535;
     uint16_t len;
     uint32_t experimenter == 0x2320;