--- openflow-2013-01-23.h	2015-07-23 09:54:17.488479376 -0700
+++ openflow-2013-06-21.h	2015-07-23 09:54:17.492479376 -0700
@@ -509,7 +509,7 @@
     uint32_t      grid_span;  /* The size of the grid for this port */
     uint32_t      tx_pwr;     /* tx power setting */
 };
-OFP_ASSERT(sizeof(struct ofp_port_mod_prop_optical) == 48);
+OFP_ASSERT(sizeof(struct ofp_port_mod_prop_optical) == 24);
 
 /* Experimenter port mod property. */
 struct ofp_port_mod_prop_experimenter {