diff --git a/lib/bcoin/chaindb.js b/lib/bcoin/chaindb.js
index ff7b5d07..882ec795 100644
--- a/lib/bcoin/chaindb.js
+++ b/lib/bcoin/chaindb.js
@@ -456,7 +456,7 @@ ChainDB.prototype.getEntry = function getEntry(hash, callback) {
     return utils.nextTick(callback);
 
   return this.getHash(hash, function(err, hash) {
-    if (err && err.type !== 'NotFoundError')
+    if (err)
       return callback(err);
 
     if (!hash)
diff --git a/lib/bcoin/lowlevelup.js b/lib/bcoin/lowlevelup.js
index 4ac8086b..a1309267 100644
--- a/lib/bcoin/lowlevelup.js
+++ b/lib/bcoin/lowlevelup.js
@@ -124,10 +124,8 @@ LowlevelUp.prototype.get = function get(key, options, callback) {
 
   return this.binding.get(key, options, function(err, result) {
     if (err) {
-      if (err.notFound || /not\s*found/i.test(err.message)) {
-        err.notFound = true;
-        err.type = 'NotFoundError';
-      }
+      if (isNotFound(err))
+        return callback();
       return callback(err);
     }
     return callback(null, result);
@@ -222,7 +220,7 @@ LowlevelUp.prototype.approximateSize = function approximateSize(start, end, call
 
 LowlevelUp.prototype.has = function has(key, callback) {
   return this.get(key, function(err, value) {
-    if (err && err.type !== 'NotFoundError')
+    if (err)
       return callback(err);
 
     return callback(null, value != null);
@@ -239,7 +237,7 @@ LowlevelUp.prototype.has = function has(key, callback) {
 
 LowlevelUp.prototype.fetch = function fetch(key, parse, callback) {
   return this.get(key, function(err, value) {
-    if (err && err.type !== 'NotFoundError')
+    if (err)
       return callback(err);
 
     if (!value)
@@ -265,6 +263,8 @@ LowlevelUp.prototype.iterate = function iterate(options, callback) {
   var items = [];
   var iter, opt;
 
+  assert(this.loaded, 'Cannot use database before it is loaded.');
+
   opt = {
     gte: options.gte,
     lte: options.lte,
@@ -354,7 +354,7 @@ LowlevelUp.prototype.lookup = function lookup(options, callback) {
 
     utils.forEachSerial(keys, function(key, next) {
       self.get(key, function(err, value) {
-        if (err && err.type !== 'NotFoundError')
+        if (err)
           return callback(err);
 
         if (!value)
@@ -381,6 +381,19 @@ LowlevelUp.prototype.lookup = function lookup(options, callback) {
   });
 };
 
+/*
+ * Helpers
+ */
+
+function isNotFound(err) {
+  if (!err)
+    return false;
+
+  return err.notFound
+    || err.type === 'NotFoundError'
+    || /not\s*found/i.test(err.message);
+}
+
 /*
  * Expose
  */
diff --git a/lib/bcoin/txdb.js b/lib/bcoin/txdb.js
index 0c0f3e2a..58ba1bc4 100644
--- a/lib/bcoin/txdb.js
+++ b/lib/bcoin/txdb.js
@@ -215,7 +215,7 @@ TXDB.prototype._addOrphan = function _addOrphan(key, hash, index, callback) {
   var p;
 
   this.db.get('o/' + key, function(err, buf) {
-    if (err && err.type !== 'NotFoundError')
+    if (err)
       return callback(err);
 
     p = new BufferWriter();
diff --git a/lib/bcoin/walletdb.js b/lib/bcoin/walletdb.js
index d4db8c8f..7c6290d8 100644
--- a/lib/bcoin/walletdb.js
+++ b/lib/bcoin/walletdb.js
@@ -431,8 +431,8 @@ WalletDB.prototype.get = function get(id, callback) {
   }
 
   this.db.get('w/' + id, function(err, data) {
-    if (err && err.type !== 'NotFoundError')
-      return callback();
+    if (err)
+      return callback(err);
 
     if (!data)
       return callback();
@@ -577,7 +577,7 @@ WalletDB.prototype.getAccount = function getAccount(id, name, callback) {
       return callback();
 
     self.db.get('a/' + id + '/' + index, function(err, data) {
-      if (err && err.type !== 'NotFoundError')
+      if (err)
         return callback(err);
 
       if (!data)
@@ -640,8 +640,8 @@ WalletDB.prototype.getAccountIndex = function getAccountIndex(id, name, callback
     return callback(null, name);
 
   this.db.get('i/' + id + '/' + name, function(err, index) {
-    if (err && err.type !== 'NotFoundError')
-      return callback();
+    if (err)
+      return callback(err);
 
     if (!index)
       return callback(null, -1);