diff --git a/src/main/java/com/sosnitzka/taiga/traits/TraitHeroic.java b/src/main/java/com/sosnitzka/taiga/traits/TraitHeroic.java
index a9ea4c6..8966ef4 100644
--- a/src/main/java/com/sosnitzka/taiga/traits/TraitHeroic.java
+++ b/src/main/java/com/sosnitzka/taiga/traits/TraitHeroic.java
@@ -16,11 +16,15 @@ public class TraitHeroic extends AbstractTrait {
     public float damage(ItemStack tool, EntityLivingBase player, EntityLivingBase target, float damage, float newDamage, boolean isCritical) {
         int durability = ToolHelper.getCurrentDurability(tool);
         int durabilitymax = ToolHelper.getMaxDurability(tool);
+        int safeDenominator = durabilitymax - durability - 1;
+        if (safeDenominator <= 0) {
+            safeDenominator = 1;
+        }
         float calc;
         if ((durability * durabilitymax / (durabilitymax - durability - 1)) != 0) {
-            calc = newDamage + (newDamage / 2) / (durability * durabilitymax / (durabilitymax - durability - 1));
+            calc = newDamage + (newDamage / 2) / (durability * durabilitymax / safeDenominator);
         } else {
-            calc = newDamage + (newDamage / 2) / ((durability * durabilitymax / (durabilitymax - durability - 1)) + 1);
+            calc = newDamage + (newDamage / 2) / ((durability * durabilitymax / safeDenominator) + 1);
         }
         if ((float) durability < (float) (0.10 * durabilitymax) || player.getHealth() < player.getMaxHealth() / 8 || (target.getHealth() == target.getMaxHealth() && random.nextFloat() > 0.8)) {
             return super.damage(tool, player, target, damage, calc, isCritical);