diff --git a/lib/6to5/generation/node/index.js b/lib/6to5/generation/node/index.js
index 42daaafaec..bedd7ba60a 100644
--- a/lib/6to5/generation/node/index.js
+++ b/lib/6to5/generation/node/index.js
@@ -13,7 +13,7 @@ var find = function (obj, node, parent) {
   for (var i = 0; i < types.length; i++) {
     var type = types[i];
 
-    if (t["is" + type](node)) {
+    if (t.is(type, node)) {
       var fn = obj[type];
       result = fn(node, parent);
       if (result != null) break;
diff --git a/lib/6to5/types/index.js b/lib/6to5/types/index.js
index c00e9506af..1e2f6487d9 100644
--- a/lib/6to5/types/index.js
+++ b/lib/6to5/types/index.js
@@ -7,14 +7,18 @@ t.NATIVE_TYPE_NAMES = ["Array", "Object", "Number", "Boolean", "Date", "Array",
 
 //
 
-var addAssert = function (type, is) {
+function registerType(type, skipAliases) {
+  var is = t["is" + type] = function (node, opts) {
+    return t.is(type, node, opts, skipAliases);
+  };
+
   t["assert" + type] = function (node, opts) {
     opts = opts || {};
     if (!is(node, opts)) {
       throw new Error("Expected type " + JSON.stringify(type) + " with option " + JSON.stringify(opts));
     }
   };
-};
+}
 
 t.STATEMENT_OR_BLOCK_KEYS = ["consequent", "body"];
 
@@ -22,14 +26,48 @@ t.STATEMENT_OR_BLOCK_KEYS = ["consequent", "body"];
 
 t.VISITOR_KEYS = require("./visitor-keys");
 
-_.each(t.VISITOR_KEYS, function (keys, type) {
-  var is = t["is" + type] = function (node, opts) {
-    return node && node.type === type && t.shallowEqual(node, opts);
-  };
+t.ALIAS_KEYS = require("./alias-keys");
 
-  addAssert(type, is);
+t.FLIPPED_ALIAS_KEYS = {};
+
+_.each(t.VISITOR_KEYS, function (keys, type) {
+  registerType(type, true);
 });
 
+_.each(t.ALIAS_KEYS, function (aliases, type) {
+  _.each(aliases, function (alias) {
+    var types = t.FLIPPED_ALIAS_KEYS[alias] = t.FLIPPED_ALIAS_KEYS[alias] || [];
+    types.push(type);
+  });
+});
+
+_.each(t.FLIPPED_ALIAS_KEYS, function (types, type) {
+  t[type.toUpperCase() + "_TYPES"] = types;
+  registerType(type, false);
+});
+
+t.is = function (type, node, opts, skipAliases) {
+  if (!node) return;
+
+  var typeMatches = (type === node.type);
+
+  if (!typeMatches && !skipAliases) {
+    var aliases = t.FLIPPED_ALIAS_KEYS[type];
+
+    if (typeof aliases !== 'undefined')
+      typeMatches = aliases.indexOf(node.type) > -1;
+  }
+
+  if (!typeMatches) {
+    return false;
+  }
+
+  if (typeof opts !== 'undefined')
+    return t.shallowEqual(node, opts);
+
+  return true;
+};
+
 //
 
 t.BUILDER_KEYS = _.defaults(require("./builder-keys"), t.VISITOR_KEYS);
@@ -45,29 +83,6 @@ _.each(t.BUILDER_KEYS, function (keys, type) {
   };
 });
 
-//
-
-t.ALIAS_KEYS = require("./alias-keys");
-
-t.FLIPPED_ALIAS_KEYS = {};
-
-_.each(t.ALIAS_KEYS, function (aliases, type) {
-  _.each(aliases, function (alias) {
-    var types = t.FLIPPED_ALIAS_KEYS[alias] = t.FLIPPED_ALIAS_KEYS[alias] || [];
-    types.push(type);
-  });
-});
-
-_.each(t.FLIPPED_ALIAS_KEYS, function (types, type) {
-  t[type.toUpperCase() + "_TYPES"] = types;
-
-  var is = t["is" + type] = function (node, opts) {
-    return node && types.indexOf(node.type) >= 0 && t.shallowEqual(node, opts);
-  };
-
-  addAssert(type, is);
-});
-
 /**
  * Description
  *
@@ -139,17 +154,17 @@ t.toSequenceExpression = function (nodes, scope) {
 //
 
 t.shallowEqual = function (actual, expected) {
-  var same = true;
+  var keys = Object.keys(expected);
+  var key;
 
-  if (expected) {
-    _.each(expected, function (val, key) {
-      if (actual[key] !== val) {
-        return same = false;
-      }
-    });
+  for (var i = 0; i < keys.length; i++) {
+    key = keys[i];
+
+    if (actual[key] !== expected[key])
+      return false;
   }
 
-  return same;
+  return true;
 };
 
 /**