diff --git a/src/transaction/makeOutput.js b/src/transaction/makeOutput.js
index d8eb1f3..820f3c3 100644
--- a/src/transaction/makeOutput.js
+++ b/src/transaction/makeOutput.js
@@ -3,10 +3,13 @@
  * Create an Output from a Condition.
  * Note: Assumes the given Condition was generated from a single public key (e.g. a Ed25519 Condition)
  * @param {object} condition Condition (e.g. a Ed25519 Condition from `makeEd25519Condition()`)
- * @param {number} amount Amount of the output
+ * @param {string} amount Amount of the output
  * @returns {object} An Output usable in a Transaction
  */
-export default function makeOutput(condition, amount = 1) {
+export default function makeOutput(condition, amount = '1') {
+    if (typeof amount !== 'string') {
+        throw new TypeError('`amount` must be of type string')
+    }
     return {
         'amount': amount,
         condition,