diff --git a/lib/6to5/transformation/transform.js b/lib/6to5/transformation/transform.js
index 0d2440e3f6..34583744c8 100644
--- a/lib/6to5/transformation/transform.js
+++ b/lib/6to5/transformation/transform.js
@@ -20,11 +20,12 @@ transform.fromAst = function (ast, code, opts) {
 };
 
 transform._ensureTransformerNames = function (type, keys) {
-  _.each(keys, function (key) {
+  for (var i in keys) {
+    var key = keys[i];
     if (!_.has(transform.transformers, key)) {
       throw new ReferenceError("unknown transformer " + key + " specified in " + type);
     }
-  });
+  }
 };
 
 transform.transformers = {};
diff --git a/lib/6to5/transformation/transformers/es6-default-parameters.js b/lib/6to5/transformation/transformers/es6-default-parameters.js
index 304061943e..69fa62755d 100644
--- a/lib/6to5/transformation/transformers/es6-default-parameters.js
+++ b/lib/6to5/transformation/transformers/es6-default-parameters.js
@@ -26,7 +26,7 @@ exports.Function = function (node, parent, file, scope) {
       var check = function (node, parent) {
         if (!t.isIdentifier(node) || !t.isReferenced(node, parent)) return;
 
-        if (_.contains(ids, node.name)) {
+        if (ids.indexOf(node.name) >= 0) {
           throw file.errorWithNode(node, "Temporal dead zone - accessing a variable before it's initialized");
         }
 
@@ -41,7 +41,7 @@ exports.Function = function (node, parent, file, scope) {
 
     // we're accessing a variable that's already defined within this function
     var has = scope.get(param.name);
-    if (has && !_.contains(node.params, has)) {
+    if (has && node.params.indexOf(has) < 0) {
       iife = true;
     }
   }
diff --git a/lib/6to5/transformation/transformers/es6-let-scoping.js b/lib/6to5/transformation/transformers/es6-let-scoping.js
index a173eb9aa2..4e209b37d6 100644
--- a/lib/6to5/transformation/transformers/es6-let-scoping.js
+++ b/lib/6to5/transformation/transformers/es6-let-scoping.js
@@ -270,9 +270,10 @@ LetScoping.prototype.initialiseLoopLets = function () {
     }
 
     if (isLet(node)) {
-      _.each(node.declarations, function (declar) {
+      for (var i in node.declarations) {
+        var declar = node.declarations[i];
         declar.init = declar.init || t.identifier("undefined");
-      });
+      }
     }
   });
 };
diff --git a/lib/6to5/transformation/transformers/es6-modules.js b/lib/6to5/transformation/transformers/es6-modules.js
index 47ffaba321..039d716aa2 100644
--- a/lib/6to5/transformation/transformers/es6-modules.js
+++ b/lib/6to5/transformation/transformers/es6-modules.js
@@ -10,11 +10,13 @@ exports.ImportDeclaration = function (node, parent, file) {
   var nodes = [];
 
   if (node.specifiers.length) {
+    if (!file.moduleFormatter.importSpecifier) return;
     for (var i in node.specifiers) {
       file.moduleFormatter.importSpecifier(node.specifiers[i], node, nodes, parent);
     }
   } else {
-    file.moduleFormatter.import(node, nodes, parent);
+    if (!file.moduleFormatter.importDeclaration) return;
+    file.moduleFormatter.importDeclaration(node, nodes, parent);
   }
 
   inheritsComments(node, nodes);
@@ -33,8 +35,10 @@ exports.ExportDeclaration = function (node, parent, file) {
       declar.init = declar.init || t.identifier("undefined");
     }
 
-    file.moduleFormatter.export(node, nodes, parent);
+    if (!file.moduleFormatter.exportDeclaration) return;
+    file.moduleFormatter.exportDeclaration(node, nodes, parent);
   } else {
+    if (!file.moduleFormatter.exportSpecifier) return;
     for (var i in node.specifiers) {
       file.moduleFormatter.exportSpecifier(node.specifiers[i], node, nodes, parent);
     }