diff --git a/packages/medusa/src/services/shipping-option.js b/packages/medusa/src/services/shipping-option.js
index 597a65fc88..db65235491 100644
--- a/packages/medusa/src/services/shipping-option.js
+++ b/packages/medusa/src/services/shipping-option.js
@@ -252,10 +252,13 @@ class ShippingOptionService extends BaseService {
       }
     }
 
-    if (price.type === "flat_rate" && (!price.amount || price.amount <= 0)) {
+    if (
+      price.type === "flat_rate" &&
+      (price.amount === undefined || price.amount < 0)
+    ) {
       throw new MedusaError(
         MedusaError.Types.INVALID_DATA,
-        "Flat rate prices must have be zero or have a postive amount field."
+        "Flat rate prices must be zero or have a postive amount field."
       )
     }