diff --git a/lib/blockchain/chain.js b/lib/blockchain/chain.js
index 113da385..4c12c3f7 100644
--- a/lib/blockchain/chain.js
+++ b/lib/blockchain/chain.js
@@ -220,7 +220,7 @@ Chain.prototype._close = function close() {
 /**
  * Perform all necessary contextual verification on a block.
  * @private
- * @param {Block|MerkleBlock} block
+ * @param {Block} block
  * @param {ChainEntry} prev
  * @returns {Promise} - Returns {@link ContextResult}.
  */
@@ -509,7 +509,7 @@ Chain.prototype.setDeploymentState = function setDeploymentState(state) {
  * can skip this.
  * @private
  * @see https://github.com/bitcoin/bips/blob/master/bip-0030.mediawiki
- * @param {Block|MerkleBlock} block
+ * @param {Block} block
  * @param {ChainEntry} prev
  * @returns {Promise}
  */
@@ -709,7 +709,7 @@ Chain.prototype.findFork = co(function* findFork(fork, longer) {
  * is received.
  * @private
  * @param {ChainEntry} competitor - The competing chain's tip.
- * @param {Block|MerkleBlock} block - The being being added.
+ * @param {Block} block - The being being added.
  * @returns {Promise}
  */
 
@@ -760,7 +760,7 @@ Chain.prototype.reorganize = co(function* reorganize(competitor, block) {
  * will reset the chain to the fork block.
  * @private
  * @param {ChainEntry} competitor - The competing chain's tip.
- * @param {Block|MerkleBlock} block - The being being added.
+ * @param {Block} block - The being being added.
  * @returns {Promise}
  */
 
@@ -877,7 +877,7 @@ Chain.prototype.reconnect = co(function* reconnect(entry) {
  * reorganize the chain (a higher fork).
  * @private
  * @param {ChainEntry} entry
- * @param {Block|MerkleBlock} block
+ * @param {Block} block
  * @param {ChainEntry} prev
  * @returns {Promise}
  */
@@ -937,7 +937,7 @@ Chain.prototype.setBestChain = co(function* setBestChain(entry, block, prev) {
  * Save block on an alternate chain.
  * @private
  * @param {ChainEntry} entry
- * @param {Block|MerkleBlock} block
+ * @param {Block} block
  * @param {ChainEntry} prev
  * @returns {Promise}
  */
@@ -1575,22 +1575,13 @@ Chain.prototype.has = co(function* has(hash) {
 });
 
 /**
- * Test the chain to see if it has recently seen a block.
- * @param {Hash} hash
- * @returns {Boolean}
+ * Find the corresponding block entry by hash or height.
+ * @param {Hash|Number} hash/height
+ * @returns {Promise} - Returns {@link ChainEntry}.
  */
 
-Chain.prototype.seen = function seen(hash) {
-  if (this.hasOrphan(hash))
-    return true;
-
-  if (this.locker.has(hash))
-    return true;
-
-  if (this.invalid.has(hash))
-    return true;
-
-  return this.db.hasCache(hash);
+Chain.prototype.getEntry = function getEntry(hash) {
+  return this.db.getEntry(hash);
 };
 
 /**
@@ -1603,6 +1594,16 @@ Chain.prototype.hasEntry = function hasEntry(hash) {
   return this.db.hasEntry(hash);
 };
 
+/**
+ * Get an orphan block.
+ * @param {Hash} hash
+ * @returns {Block}
+ */
+
+Chain.prototype.getOrphan = function getOrphan(hash) {
+  return this.orphanMap[hash] || null;
+};
+
 /**
  * Test the chain to see if it contains an orphan.
  * @param {Hash} hash
@@ -1610,7 +1611,7 @@ Chain.prototype.hasEntry = function hasEntry(hash) {
  */
 
 Chain.prototype.hasOrphan = function hasOrphan(hash) {
-  return !!this.getOrphan(hash);
+  return this.orphanMap[hash] != null;
 };
 
 /**
@@ -1623,26 +1624,6 @@ Chain.prototype.hasPending = function hasPending(hash) {
   return this.locker.hasPending(hash);
 };
 
-/**
- * Find the corresponding block entry by hash or height.
- * @param {Hash|Number} hash/height
- * @returns {Promise} - Returns {@link ChainEntry}.
- */
-
-Chain.prototype.getEntry = function getEntry(hash) {
-  return this.db.getEntry(hash);
-};
-
-/**
- * Get an orphan block.
- * @param {Hash} hash
- * @returns {Block|MerkleBlock|MemBlock}
- */
-
-Chain.prototype.getOrphan = function getOrphan(hash) {
-  return this.orphanMap[hash] || null;
-};
-
 /**
  * Get coin viewpoint.
  * @param {TX} tx
@@ -1719,7 +1700,7 @@ Chain.prototype.getProgress = function getProgress() {
 
 /**
  * Calculate chain locator (an array of hashes).
- * @param {(Number|Hash)?} start - Height or hash to treat as the tip.
+ * @param {Hash} start - Height or hash to treat as the tip.
  * The current tip will be used if not present. Note that this can be a
  * non-existent hash, which is useful for headers-first locators.
  * @returns {Promise} - Returns {@link Hash}[].
@@ -1737,7 +1718,7 @@ Chain.prototype.getLocator = co(function* getLocator(start) {
 /**
  * Calculate chain locator without a lock.
  * @private
- * @param {(Number|Hash)?} start
+ * @param {Hash} start
  * @returns {Promise}
  */
 
@@ -1749,16 +1730,12 @@ Chain.prototype._getLocator = co(function* getLocator(start) {
   if (start == null)
     start = this.tip.hash;
 
+  assert(typeof start === 'string');
+
   entry = yield this.db.getEntry(start);
 
   if (!entry) {
-    // We could simply return `start` here,
-    // but there is no required "spacing"
-    // for locator hashes. Pretend this hash
-    // is our tip. This is useful for
-    // getheaders.
-    if (typeof start === 'string')
-      hashes.push(start);
+    hashes.push(start);
     entry = this.tip;
   }
 
@@ -1860,7 +1837,7 @@ Chain.prototype.getCurrentTarget = co(function* getCurrentTarget() {
 /**
  * Calculate the target based on the passed-in chain entry.
  * @param {ChainEntry} prev - Previous entry.
- * @param {Block|MerkleBlock|null} - Current block.
+ * @param {Block} - Current block.
  * @returns {Promise} - returns Number
  * (target is in compact/mantissa form).
  */
@@ -1882,8 +1859,9 @@ Chain.prototype.getTargetAsync = co(function* getTargetAsync(block, prev) {
 /**
  * Calculate the target synchronously. _Must_
  * have ancestors pre-allocated.
- * @param {Block|MerkleBlock|null} - Current block.
+ * @param {Block} - Current block.
  * @param {ChainEntry} prev - Previous entry.
+ * @param {ChainEntry[]} ancestors
  * @returns {Promise} - returns Number
  * (target is in compact/mantissa form).
  */