diff --git a/lib/bcoin/input.js b/lib/bcoin/input.js
index f7b4eeac..eba9ce51 100644
--- a/lib/bcoin/input.js
+++ b/lib/bcoin/input.js
@@ -25,8 +25,11 @@ function Input(options, tx) {
   this.witness = bcoin.script.witness(options.witness);
   this._mutable = !tx || (tx instanceof bcoin.mtx);
 
-  if (options.coin)
+  if (options.coin) {
     this.coin = bcoin.coin(options.coin);
+    assert(typeof this.coin.hash === 'string');
+    assert(typeof this.coin.index === 'number');
+  }
 
   if (Buffer.isBuffer(this.prevout.hash))
     this.prevout.hash = utils.toHex(this.prevout.hash);
@@ -153,7 +156,7 @@ Input.prototype.inspect = function inspect() {
   var coin;
 
   if (this.coin) {
-    coin = this.coin.inspect();
+    coin = this.coin;
   } else {
     coin = {
       type: 'unknown',