diff --git a/lib/primitives/block.js b/lib/primitives/block.js
index cf64b744..e16a95e3 100644
--- a/lib/primitives/block.js
+++ b/lib/primitives/block.js
@@ -366,12 +366,13 @@ Block.prototype.getMerkleRoot = function getMerkleRoot(enc) {
  */
 
 Block.prototype.getWitnessNonce = function getWitnessNonce() {
-  var coinbase = this.txs[0];
-  var input;
+  var coinbase, input;
 
-  if (!coinbase)
+  if (this.txs.length === 0)
     return null;
 
+  coinbase = this.txs[0];
+
   if (coinbase.inputs.length !== 1)
     return null;
 
@@ -394,12 +395,13 @@ Block.prototype.getWitnessNonce = function getWitnessNonce() {
  */
 
 Block.prototype.getCommitmentHash = function getCommitmentHash(enc) {
-  var coinbase = this.txs[0];
-  var i, hash, output;
+  var i, coinbase, hash, output;
 
-  if (!coinbase)
+  if (this.txs.length === 0)
     return null;
 
+  coinbase = this.txs[0];
+
   for (i = coinbase.outputs.length - 1; i >= 0; i--) {
     output = coinbase.outputs[i];
     if (output.script.isCommitment()) {