diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index 6034ee94..f52df67b 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -247,8 +247,10 @@ Mempool.prototype.addBlock = function addBlock(block, callback, force) {
       if (err)
         return next(err);
 
-      if (!entry)
-        return self.removeOrphan(hash, next);
+      if (!entry) {
+        self.removeOrphan(hash);
+        return next();
+      }
 
       self.removeUnchecked(entry, false, function(err) {
         if (err)
@@ -380,29 +382,21 @@ Mempool.prototype.limitMempoolSize = function limitMempoolSize(entryHash, callba
 
 /**
  * Purge orphan transactions from the mempool.
- * @param {Function} callback
  */
 
-Mempool.prototype.limitOrphans = function limitOrphans(callback) {
-  var self = this;
+Mempool.prototype.limitOrphans = function limitOrphans() {
   var orphans = Object.keys(this.orphans);
   var i, hash;
 
-  (function next(err) {
-    if (err)
-      return callback(err);
-
-    if (self.totalOrphans <= constants.mempool.MAX_ORPHAN_TX)
-      return callback();
-
+  while (this.totalOrphans > constants.mempool.MAX_ORPHAN_TX) {
     i = bcoin.ec.rand(0, orphans.length);
     hash = orphans[i];
     orphans.splice(i, 1);
 
     bcoin.debug('Removing orphan %s from mempool.', utils.revHex(hash));
 
-    self.removeOrphan(hash, next);
-  })();
+    this.removeOrphan(hash);
+  }
 };
 
 /**
@@ -606,20 +600,13 @@ Mempool.prototype.getRange = function getRange(options, callback) {
  */
 
 Mempool.prototype.has = function has(hash, callback) {
-  var self = this;
-
   if (this.locker.hasPending(hash))
     return utils.asyncify(callback)(null, true);
 
-  return this.hasTX(hash, function(err, exists) {
-    if (err)
-      return callback(err);
+  if (this.hasOrphan(hash))
+    return utils.asyncify(callback)(null, true);
 
-    if (exists)
-      return callback(null, true);
-
-    self.hasOrphan(hash, callback);
-  });
+  return this.hasTX(hash, callback);
 };
 
 /**
@@ -722,8 +709,10 @@ Mempool.prototype.addTX = function addTX(tx, callback, force) {
             if (err)
               return callback(err);
 
-            if (!tx.hasCoins())
-              return self.storeOrphan(tx, callback);
+            if (!tx.hasCoins()) {
+              self.storeOrphan(tx);
+              return callback();
+            }
 
             entry = MempoolEntry.fromTX(tx, self.chain.height);
 
@@ -769,6 +758,7 @@ Mempool.prototype.addTX = function addTX(tx, callback, force) {
 
 Mempool.prototype.addUnchecked = function addUnchecked(entry, callback, force) {
   var self = this;
+  var resolved;
 
   var unlock = this._lock(addUnchecked, [entry, callback], force);
   if (!unlock)
@@ -788,34 +778,31 @@ Mempool.prototype.addUnchecked = function addUnchecked(entry, callback, force) {
 
     bcoin.debug('Added tx %s to the mempool.', entry.tx.rhash);
 
-    self.resolveOrphans(entry.tx, function(err, resolved) {
-      if (err)
-        return callback(err);
+    resolved = self.resolveOrphans(entry.tx);
 
-      utils.forEachSerial(resolved, function(tx, next) {
-        var entry = MempoolEntry.fromTX(tx, self.chain.height);
-        self.verify(entry, function(err) {
+    utils.forEachSerial(resolved, function(tx, next) {
+      var entry = MempoolEntry.fromTX(tx, self.chain.height);
+      self.verify(entry, function(err) {
+        if (err) {
+          if (err.type === 'VerifyError') {
+            bcoin.debug('Could not resolve orphan %s: %s.',
+              tx.rhash,
+              err.message);
+            return next();
+          }
+          self.emit('error', err);
+          return next();
+        }
+        self.addUnchecked(entry, function(err) {
           if (err) {
-            if (err.type === 'VerifyError') {
-              bcoin.debug('Could not resolve orphan %s: %s.',
-                tx.rhash,
-                err.message);
-              return next();
-            }
             self.emit('error', err);
             return next();
           }
-          self.addUnchecked(entry, function(err) {
-            if (err) {
-              self.emit('error', err);
-              return next();
-            }
-            bcoin.debug('Resolved orphan %s in mempool.', entry.tx.rhash);
-            next();
-          }, true);
-        });
-      }, callback);
-    });
+          bcoin.debug('Resolved orphan %s in mempool.', entry.tx.rhash);
+          next();
+        }, true);
+      });
+    }, callback);
   });
 };
 
@@ -840,31 +827,28 @@ Mempool.prototype.removeUnchecked = function removeUnchecked(entry, limit, callb
     if (err)
       return callback(err);
 
-    self.removeOrphan(entry.tx, function(err) {
+    self.removeOrphan(entry.tx);
+
+    self._removeUnchecked(entry, limit, function(err) {
       if (err)
         return callback(err);
 
-      self._removeUnchecked(entry, limit, function(err) {
-        if (err)
-          return callback(err);
+      self.spent -= entry.tx.inputs.length;
+      self.size -= self.memUsage(entry.tx);
+      self.total--;
 
-        self.spent -= entry.tx.inputs.length;
-        self.size -= self.memUsage(entry.tx);
-        self.total--;
-
-        if (limit) {
-          rate = Math.floor(entry.fees * 1000 / entry.size);
-          rate += self.minReasonableFee;
-          if (rate > self.minFeeRate) {
-            self.minFeeRate = rate;
-            self.blockSinceBump = false;
-          }
+      if (limit) {
+        rate = Math.floor(entry.fees * 1000 / entry.size);
+        rate += self.minReasonableFee;
+        if (rate > self.minFeeRate) {
+          self.minFeeRate = rate;
+          self.blockSinceBump = false;
         }
+      }
 
-        self.emit('remove tx', entry.tx);
+      self.emit('remove tx', entry.tx);
 
-        return callback();
-      });
+      return callback();
     });
   });
 };
@@ -1097,17 +1081,15 @@ Mempool.prototype.countAncestors = function countAncestors(tx, callback) {
 /**
  * Store an orphaned transaction.
  * @param {TX} tx
- * @param {Function} callback
  */
 
-Mempool.prototype.storeOrphan = function storeOrphan(tx, callback, force) {
-  var self = this;
+Mempool.prototype.storeOrphan = function storeOrphan(tx) {
   var prevout = {};
   var i, hash, batch, input, prev;
 
   if (tx.getSize() > 5000) {
     bcoin.debug('Ignoring large orphan: %s', tx.rhash);
-    return callback();
+    return;
   }
 
   hash = tx.hash('hex');
@@ -1134,10 +1116,7 @@ Mempool.prototype.storeOrphan = function storeOrphan(tx, callback, force) {
 
   bcoin.debug('Added orphan %s to mempool.', tx.rhash);
 
-  if (this.totalOrphans > constants.mempool.MAX_ORPHAN_TX)
-    return this.limitOrphans(callback);
-
-  return callback();
+  this.limitOrphans();
 };
 
 /**
@@ -1187,45 +1166,38 @@ Mempool.prototype.getHistory = function getHistory(callback) {
   }, callback);
 };
 
-/**
- * Get hashes of all orphans a transaction hash potentially resolves.
- * @param {Hash} hash - Resolving transaction.
- * @param {Function} callback - Return [Error, {@link Hash}[]].
- */
-
-Mempool.prototype.getWaiting = function getWaiting(hash, callback) {
-  return callback(null, this.waiting[hash] || []);
-};
-
 /**
  * Retrieve an orphan transaction.
- * @param {Hash} orphanHash
- * @param {Function} callback - Returns [Error, {@link TX}].
+ * @param {Hash} hash
+ * @returns {TX}
  */
 
-Mempool.prototype.getOrphan = function getOrphan(orphanHash, callback) {
-  var self = this;
-  var orphan = this.orphans[orphanHash];
+Mempool.prototype.getOrphan = function getOrphan(hash) {
+  var orphan = this.orphans[hash];
 
   if (!orphan)
-    return callback();
+    return;
 
   try {
     orphan = bcoin.tx.fromExtended(orphan, true);
   } catch (e) {
-    return callback(e);
+    delete this.orphans[hash];
+    bcoin.debug('%s %s',
+      'Warning: possible memory corruption.',
+      'Orphan failed deserialization.');
+    return;
   }
 
-  return callback(null, orphan);
+  return orphan;
 };
 
 /**
- * @param {Hash} orphanHash
- * @param {Function} callback - Returns [Error, Boolean].
+ * @param {Hash} hash
+ * @returns {Boolean}
  */
 
-Mempool.prototype.hasOrphan = function hasOrphan(orphanHash, callback) {
-  return callback(null, this.orphans[orphanHash] != null);
+Mempool.prototype.hasOrphan = function hasOrphan(hash) {
+  return this.orphans[hash] != null;
 };
 
 /**
@@ -1234,107 +1206,81 @@ Mempool.prototype.hasOrphan = function hasOrphan(orphanHash, callback) {
  * Deletes all orphan entries and
  * returns orphan hashes.
  * @param {TX} tx
- * @param {Function} callback - Returns [Error, {@link Hash}[]].
+ * @returns {Array} Resolved
  */
 
-Mempool.prototype.resolveOrphans = function resolveOrphans(tx, callback, force) {
-  var self = this;
+Mempool.prototype.resolveOrphans = function resolveOrphans(tx) {
   var hash = tx.hash('hex');
   var resolved = [];
+  var hashes = this.waiting[hash];
+  var i, orphanHash, orphan;
 
-  this.getWaiting(hash, function(err, hashes) {
-    if (err)
-      return callback(err);
+  if (!hashes)
+    return resolved;
 
-    utils.forEachSerial(hashes, function(orphanHash, next, i) {
-      self.getOrphan(orphanHash, function(err, orphan) {
-        if (err)
-          return next(err);
+  for (i = 0; i < hashes.length; i++) {
+    orphanHash = hashes[i];
+    orphan = this.getOrphan(orphanHash);
 
-        if (!orphan)
-          return next();
+    if (!orphan)
+      continue;
 
-        orphan.fillCoins(tx);
+    orphan.fillCoins(tx);
 
-        if (orphan.hasCoins()) {
-          self.totalOrphans--;
-          delete self.orphans[orphanHash];
-          resolved.push(orphan);
-          return next();
-        }
+    if (orphan.hasCoins()) {
+      this.totalOrphans--;
+      delete this.orphans[orphanHash];
+      resolved.push(orphan);
+      continue;
+    }
 
-        self.orphans[orphanHash] = orphan.toExtended(true);
+    this.orphans[orphanHash] = orphan.toExtended(true);
+  }
 
-        next();
-      });
-    }, function(err) {
-      if (err)
-        return callback(err);
+  delete this.waiting[hash];
 
-      delete self.waiting[hash];
-
-      return callback(null, resolved);
-    });
-  });
+  return resolved;
 };
 
 /**
  * Remove a transaction from the mempool.
  * @param {TX|Hash} tx
- * @param {Function} callback
  */
 
-Mempool.prototype.removeOrphan = function removeOrphan(tx, callback) {
-  var self = this;
-  var i, prevout, hash;
+Mempool.prototype.removeOrphan = function removeOrphan(tx) {
+  var i, j, hashes, prevout, prev, hash;
 
-  function getOrphan(tx, callback) {
-    if (typeof tx === 'string')
-      return self.getOrphan(tx, callback);
-    return callback(null, tx);
+  if (typeof tx === 'string')
+    tx = this.getOrphan(tx);
+
+  if (!tx)
+    return;
+
+  hash = tx.hash('hex');
+  prevout = tx.getPrevout();
+
+  for (i = 0; i < prevout.length; i++) {
+    prev = prevout[i];
+    hashes = this.waiting[prev];
+
+    if (!hashes)
+      continue;
+
+    j = hashes.indexOf(hash);
+    if (j !== -1)
+      hashes.splice(j, 1);
+
+    if (hashes.length === 0) {
+      delete this.waiting[prev];
+      continue;
+    }
+
+    this.waiting[prev] = hashes;
   }
 
-  return getOrphan(tx, function(err, tx) {
-    if (err)
-      return callback(err);
+  delete this.orphans[hash];
 
-    if (!tx)
-      return callback();
-
-    hash = tx.hash('hex');
-    prevout = tx.getPrevout();
-
-    utils.forEachSerial(prevout, function(prev, next) {
-      self.getWaiting(prev, function(err, hashes) {
-        if (err)
-          return next(err);
-
-        if (hashes.length === 0)
-          return next();
-
-        i = hashes.indexOf(hash);
-        if (i !== -1)
-          hashes.splice(i, 1);
-
-        if (hashes.length === 0) {
-          delete self.waiting[prev];
-          return next();
-        }
-
-        self.waiting[prev] = hashes;
-
-        next();
-      });
-    }, function(err) {
-      if (err)
-        return callback(err);
-
-      delete self.orphans[hash];
-      self.totalOrphans--;
-
-      callback();
-    });
-  });
+  this.totalOrphans--;
 };
 
 /**