diff --git a/lib/recurly/pricing/subscription/calculations.js b/lib/recurly/pricing/subscription/calculations.js
index c2dfb271d..b22d02c31 100644
--- a/lib/recurly/pricing/subscription/calculations.js
+++ b/lib/recurly/pricing/subscription/calculations.js
@@ -272,7 +272,9 @@ export default class Calculations {
     const plan = this.items.plan;
     if (!plan) return { amount: 0, setup_fee: 0 };
     let price = plan.price[this.items.currency];
-    price.amount = price.unit_amount * (plan.quantity || 1);
+    let quantity = parseInt(plan.quantity, 10);
+    if (isNaN(quantity)) quantity = 1;
+    price.amount = price.unit_amount * quantity;
     return price;
   }
 
diff --git a/lib/recurly/pricing/subscription/index.js b/lib/recurly/pricing/subscription/index.js
index 2acc5937f..3d8026819 100644
--- a/lib/recurly/pricing/subscription/index.js
+++ b/lib/recurly/pricing/subscription/index.js
@@ -371,8 +371,9 @@ export default class SubscriptionPricing extends Pricing {
 
     // options.quantity, plan.quantity, 1
     if (plan && plan.quantity) quantity = plan.quantity;
-    if (options.quantity) quantity = parseInt(options.quantity, 10);
-    if (!quantity || quantity < 1) quantity = 1;
+
+    if ('quantity' in options) quantity = parseInt(options.quantity, 10);
+    if (isNaN(quantity) || quantity < 0) quantity = 1;
 
     return { currentPlan: plan, quantity, planCode, options, done };
   }