diff --git a/modules/pegasus-actor.js b/modules/pegasus-actor.js
index 93ad7b4..3d2cb25 100644
--- a/modules/pegasus-actor.js
+++ b/modules/pegasus-actor.js
@@ -1922,6 +1922,10 @@ export class PegasusActor extends Actor {
   /* -------------------------------------------- */
   processSizeBonus(rollData) {
     if (rollData.defenderTokenId) {
+      if ( !Number(this.system.biodata.sizenum) || !Number(this.system.biodata.sizebonus) ) {
+        ui.notifications.warn(`Character ${this.name} has no size value, please fix`)
+        return
+      }
       let diffSize = rollData.defenderSize - this.system.biodata.sizenum + this.system.biodata.sizebonus
       //console.log("Diffsize", diffSize)
       if (rollData.subKey == "melee-atk" || rollData.subKey == "ranged-atk") {