diff --git a/src/battle.ts b/src/battle.ts
index 939c976..079440c 100644
--- a/src/battle.ts
+++ b/src/battle.ts
@@ -457,9 +457,10 @@ export class Battle {
                 .filter(status => {return status.type === 'damage'})
                 .reduce((a, b) => a + (b.potency/100), 1);
             //multiply by resistanceChange sum
-            damage *= self.potencyEffects
+            damage *= Math.max(0, 
+                self.potencyEffects
                 .filter(status => {return status.type === 'resistance'})
-                .reduce((a, b) => a - (b.potency/100), 1);
+                .reduce((a, b) => a - (b.potency/100), 1));
             damage = Math.round(damage)
 
             this.appendLog(`(${target.team}) ${target.character.nameShort} took ${damage} damage!`);