diff --git a/lib/primitives/mtx.js b/lib/primitives/mtx.js
index 676bfca3..d6d19c5b 100644
--- a/lib/primitives/mtx.js
+++ b/lib/primitives/mtx.js
@@ -1497,6 +1497,30 @@ MTX.prototype.setLocktime = function setLocktime(locktime) {
   this.locktime = locktime;
 };
 
+/**
+ * Set sequence locktime.
+ * @param {Number} index - Input index.
+ * @param {Number} locktime
+ * @param {Boolean?} seconds
+ */
+
+MTX.prototype.setSequence = function setSequence(index, locktime, seconds) {
+  var input = this.inputs[index];
+
+  assert(input, 'Input does not exist.');
+
+  this.version = 2;
+
+  if (seconds) {
+    locktime >>>= constants.sequence.GRANULARITY;
+    locktime = constants.sequence.TYPE_FLAG | locktime;
+  } else {
+    locktime = constants.sequence.MASK & locktime;
+  }
+
+  input.sequence = locktime;
+};
+
 /**
  * Mark inputs and outputs as mutable.
  * @private