diff --git a/lib/primitives/mtx.js b/lib/primitives/mtx.js
index 7928d779..c33494e9 100644
--- a/lib/primitives/mtx.js
+++ b/lib/primitives/mtx.js
@@ -1632,7 +1632,7 @@ CoinSelector.prototype.isFull = function isFull() {
 /**
  * Test whether a coin is spendable
  * with regards to the options.
- * @param {Coin}
+ * @param {Coin} coin
  * @returns {Boolean}
  */