diff --git a/src/module/rules/rule-element/item-alteration/alteration.ts b/src/module/rules/rule-element/item-alteration/alteration.ts
index 2093d1ced6c..1094d8cabc4 100644
--- a/src/module/rules/rule-element/item-alteration/alteration.ts
+++ b/src/module/rules/rule-element/item-alteration/alteration.ts
@@ -236,7 +236,7 @@ class ItemAlteration extends foundry.abstract.DataModel<RuleElementPF2e, ItemAlt
                     const system = data.item.system;
                     const value = data.alteration.value;
                     const newValue = AELikeRuleElement.getNewValue(this.mode, system.hardness, value);
-                    system.hardness = Math.max(newValue, 0);
+                    system.hardness = Math.max(Math.trunc(newValue), 0);
                     this.#adjustCreatureShieldData(data.item);
                 }
                 return;
diff --git a/src/module/rules/rule-element/item-alteration/schemas.ts b/src/module/rules/rule-element/item-alteration/schemas.ts
index 8cf689c4149..886e210fe73 100644
--- a/src/module/rules/rule-element/item-alteration/schemas.ts
+++ b/src/module/rules/rule-element/item-alteration/schemas.ts
@@ -292,7 +292,7 @@ const ITEM_ALTERATION_VALIDATORS = {
             required: true,
             choices: ["add", "downgrade", "multiply", "override", "remove", "subtract", "upgrade"],
         }),
-        value: new fields.NumberField({ required: true, integer: true, nullable: false, positive: true } as const),
+        value: new fields.NumberField({ required: true, nullable: false, min: -20, max: 20 } as const),
     }),
     "hp-max": new ItemAlterationValidator({
         itemType: new fields.StringField({ required: true, choices: Array.from(PHYSICAL_ITEM_TYPES) }),