diff --git a/lib/blockchain/chain.js b/lib/blockchain/chain.js
index 13b02375..bfbdb59f 100644
--- a/lib/blockchain/chain.js
+++ b/lib/blockchain/chain.js
@@ -2302,19 +2302,22 @@ Chain.prototype.verifyFinal = async function verifyFinal(prev, tx, flags) {
  */
 
 Chain.prototype.getLocks = async function getLocks(prev, tx, view, flags) {
-  const mask = consensus.SEQUENCE_MASK;
-  const granularity = consensus.SEQUENCE_GRANULARITY;
-  const disableFlag = consensus.SEQUENCE_DISABLE_FLAG;
-  const typeFlag = consensus.SEQUENCE_TYPE_FLAG;
-  const hasFlag = flags & common.lockFlags.VERIFY_SEQUENCE;
+  const GRANULARITY = consensus.SEQUENCE_GRANULARITY;
+  const DISABE_FLAG = consensus.SEQUENCE_DISABLE_FLAG;
+  const TYPE_FLAG = consensus.SEQUENCE_TYPE_FLAG;
+  const MASK = consensus.SEQUENCE_MASK;
+
+  if (!(flags & common.lockFlags.VERIFY_SEQUENCE))
+    return [-1, -1];
+
+  if (tx.isCoinbase() || tx.version < 2)
+    return [-1, -1];
+
   let minHeight = -1;
   let minTime = -1;
 
-  if (tx.isCoinbase() || tx.version < 2 || !hasFlag)
-    return [minHeight, minTime];
-
   for (const {prevout, sequence} of tx.inputs) {
-    if (sequence & disableFlag)
+    if (sequence & DISABE_FLAG)
       continue;
 
     let height = view.getHeight(prevout);
@@ -2322,8 +2325,8 @@ Chain.prototype.getLocks = async function getLocks(prev, tx, view, flags) {
     if (height === -1)
       height = this.height + 1;
 
-    if ((sequence & typeFlag) === 0) {
-      height += (sequence & mask) - 1;
+    if (!(sequence & TYPE_FLAG)) {
+      height += (sequence & MASK) - 1;
       minHeight = Math.max(minHeight, height);
       continue;
     }
@@ -2334,7 +2337,7 @@ Chain.prototype.getLocks = async function getLocks(prev, tx, view, flags) {
     assert(entry, 'Database is corrupt.');
 
     let time = await entry.getMedianTime();
-    time += ((sequence & mask) << granularity) - 1;
+    time += ((sequence & MASK) << GRANULARITY) - 1;
     minTime = Math.max(minTime, time);
   }
 
diff --git a/lib/primitives/mtx.js b/lib/primitives/mtx.js
index 470581ee..6ae12cf4 100644
--- a/lib/primitives/mtx.js
+++ b/lib/primitives/mtx.js
@@ -1414,9 +1414,10 @@ MTX.prototype.setSequence = function setSequence(index, locktime, seconds) {
 
   if (seconds) {
     locktime >>>= consensus.SEQUENCE_GRANULARITY;
-    locktime = consensus.SEQUENCE_TYPE_FLAG | locktime;
+    locktime &= consensus.SEQUENCE_MASK;
+    locktime |= consensus.SEQUENCE_TYPE_FLAG;
   } else {
-    locktime = consensus.SEQUENCE_MASK & locktime;
+    locktime &= consensus.SEQUENCE_MASK;
   }
 
   input.sequence = locktime;
diff --git a/lib/primitives/tx.js b/lib/primitives/tx.js
index 88628b2d..95ef010c 100644
--- a/lib/primitives/tx.js
+++ b/lib/primitives/tx.js
@@ -1225,23 +1225,22 @@ TX.prototype.isFinal = function isFinal(height, time) {
  * Verify the absolute locktime of a transaction.
  * Called by OP_CHECKLOCKTIMEVERIFY.
  * @param {Number} index - Index of input being verified.
- * @param {Number} locktime - Locktime to verify against.
+ * @param {Number} predicate - Locktime to verify against.
  * @returns {Boolean}
  */
 
-TX.prototype.verifyLocktime = function verifyLocktime(index, locktime) {
+TX.prototype.verifyLocktime = function verifyLocktime(index, predicate) {
   const THRESHOLD = consensus.LOCKTIME_THRESHOLD;
   const input = this.inputs[index];
 
   assert(input, 'Input does not exist.');
-  assert(locktime >= 0, 'Locktime must be non-negative.');
+  assert(predicate >= 0, 'Locktime must be non-negative.');
 
-  if (!((this.locktime < THRESHOLD && locktime < THRESHOLD)
-      || (this.locktime >= THRESHOLD && locktime >= THRESHOLD))) {
+  // Locktimes must be of the same type (blocks or seconds).
+  if ((this.locktime < THRESHOLD) !== (predicate < THRESHOLD))
     return false;
-  }
 
-  if (locktime > this.locktime)
+  if (predicate > this.locktime)
     return false;
 
   if (input.sequence === 0xffffffff)
@@ -1254,38 +1253,38 @@ TX.prototype.verifyLocktime = function verifyLocktime(index, locktime) {
  * Verify the relative locktime of an input.
  * Called by OP_CHECKSEQUENCEVERIFY.
  * @param {Number} index - Index of input being verified.
- * @param {Number} locktime - Sequence locktime to verify against.
+ * @param {Number} predicate - Relative locktime to verify against.
  * @returns {Boolean}
  */
 
-TX.prototype.verifySequence = function verifySequence(index, locktime) {
+TX.prototype.verifySequence = function verifySequence(index, predicate) {
   const DISABLE_FLAG = consensus.SEQUENCE_DISABLE_FLAG;
   const TYPE_FLAG = consensus.SEQUENCE_TYPE_FLAG;
-  const SEQUENCE_MASK = consensus.SEQUENCE_MASK;
+  const MASK = consensus.SEQUENCE_MASK;
   const input = this.inputs[index];
 
   assert(input, 'Input does not exist.');
-  assert(locktime >= 0, 'Locktime must be non-negative.');
+  assert(predicate >= 0, 'Locktime must be non-negative.');
 
-  if ((locktime & DISABLE_FLAG) !== 0)
+  // For future softfork capability.
+  if (predicate & DISABLE_FLAG)
     return true;
 
+  // Version must be >=2.
   if (this.version < 2)
     return false;
 
-  if ((input.sequence & DISABLE_FLAG) !== 0)
+  // Cannot use the disable flag without
+  // the predicate also having the disable
+  // flag (for future softfork capability).
+  if (input.sequence & DISABLE_FLAG)
     return false;
 
-  const mask = TYPE_FLAG | SEQUENCE_MASK;
-  const sequence = input.sequence & mask;
-  const predicate = locktime & mask;
-
-  if (!((sequence < TYPE_FLAG && predicate < TYPE_FLAG)
-      || (sequence >= TYPE_FLAG && predicate >= TYPE_FLAG))) {
+  // Locktimes must be of the same type (blocks or seconds).
+  if ((input.sequence & TYPE_FLAG) !== (predicate & TYPE_FLAG))
     return false;
-  }
 
-  if (predicate > sequence)
+  if ((predicate & MASK) > (input.sequence & MASK))
     return false;
 
   return true;
diff --git a/lib/script/script.js b/lib/script/script.js
index c5a10d61..751ea81e 100644
--- a/lib/script/script.js
+++ b/lib/script/script.js
@@ -652,12 +652,12 @@ Script.prototype.execute = function execute(stack, flags, tx, index, value, vers
         if (stack.length === 0)
           throw new ScriptError('INVALID_STACK_OPERATION', op, ip);
 
-        let locktime = stack.getNum(-1, minimal, 5);
+        const num = stack.getNum(-1, minimal, 5);
 
-        if (locktime.isNeg())
+        if (num.isNeg())
           throw new ScriptError('NEGATIVE_LOCKTIME', op, ip);
 
-        locktime = locktime.toDouble();
+        const locktime = num.toDouble();
 
         if (!tx.verifyLocktime(index, locktime))
           throw new ScriptError('UNSATISFIED_LOCKTIME', op, ip);
@@ -678,12 +678,12 @@ Script.prototype.execute = function execute(stack, flags, tx, index, value, vers
         if (stack.length === 0)
           throw new ScriptError('INVALID_STACK_OPERATION', op, ip);
 
-        let locktime = stack.getNum(-1, minimal, 5);
+        const num = stack.getNum(-1, minimal, 5);
 
-        if (locktime.isNeg())
+        if (num.isNeg())
           throw new ScriptError('NEGATIVE_LOCKTIME', op, ip);
 
-        locktime = locktime.toDouble();
+        const locktime = num.toDouble();
 
         if (!tx.verifySequence(index, locktime))
           throw new ScriptError('UNSATISFIED_LOCKTIME', op, ip);