diff --git a/lib/6to5/transformation/transformers/es6-classes.js b/lib/6to5/transformation/transformers/es6-classes.js
index d1e48dda5b..327b1a8063 100644
--- a/lib/6to5/transformation/transformers/es6-classes.js
+++ b/lib/6to5/transformation/transformers/es6-classes.js
@@ -276,9 +276,7 @@ Class.prototype.replaceInstanceSuperReferences = function (methodNode) {
         if (callee.object.name !== "super") return;
 
         // super.test(); -> ClassName.prototype.MethodName.call(this);
-        callee.object = t.memberExpression(callee.object, callee.property, callee.computed);
-        callee.computed = false;
-        callee.property = t.identifier("call");
+        t.appendToMemberExpression(callee, t.identifier("call"));
         node.arguments.unshift(t.thisExpression());
       }
     }
diff --git a/lib/6to5/transformation/transformers/es6-spread.js b/lib/6to5/transformation/transformers/es6-spread.js
index e1dc5269d0..e3b13c8bdc 100644
--- a/lib/6to5/transformation/transformers/es6-spread.js
+++ b/lib/6to5/transformation/transformers/es6-spread.js
@@ -87,9 +87,7 @@ exports.CallExpression = function (node, parent, file, scope) {
       callee.object = t.assignmentExpression("=", temp, callee.object);
     }
 
-    callee.object = t.memberExpression(callee.object, callee.property, callee.computed);
-    callee.computed = false;
-    callee.property = t.identifier("apply");
+    t.appendToMemberExpression(callee, t.identifier("apply"));
   } else {
     node.callee = t.memberExpression(node.callee, t.identifier("apply"));
   }
diff --git a/lib/6to5/transformation/transformers/optional-core-aliasing.js b/lib/6to5/transformation/transformers/optional-core-aliasing.js
index 9c4831a87e..a23602d736 100644
--- a/lib/6to5/transformation/transformers/optional-core-aliasing.js
+++ b/lib/6to5/transformation/transformers/optional-core-aliasing.js
@@ -30,7 +30,7 @@ exports.ast = {
 
           if (!node.computed && coreHas(obj) && _.has(core[obj.name], prop.name)) {
             this.stop();
-            return t.memberExpression(t.memberExpression(file._coreId, node.object), node.property, node.computed);
+            return t.prependToMemberExpression(node, file._coreId);
           }
         } else if (t.isIdentifier(node) && !t.isMemberExpression(parent) && t.isReferenced(node, parent) && coreHas(node)) {
           // new Promise -> new _core.Promise
diff --git a/lib/6to5/types/index.js b/lib/6to5/types/index.js
index 53f5f3842e..9956aff41b 100644
--- a/lib/6to5/types/index.js
+++ b/lib/6to5/types/index.js
@@ -118,6 +118,20 @@ t.shallowEqual = function (actual, expected) {
 
 //
 
+t.appendToMemberExpression = function (member, append, computed) {
+  member.object   = t.memberExpression(member.object, member.property, member.computed);
+  member.property = append;
+  member.computed = !!computed;
+  return member;
+};
+
+t.prependToMemberExpression = function (member, append) {
+  member.object = t.memberExpression(append, member.object);
+  return member;
+};
+
+//
+
 t.isDynamic = function (node) {
   if (t.isExpressionStatement(node)) {
     return t.isDynamic(node.expression);
@@ -130,7 +144,6 @@ t.isDynamic = function (node) {
   }
 };
 
-// todo: https://github.com/eventualbuddha/ast-util/blob/9bf91c5ce8/lib/index.js#L454-L507
 t.isReferenced = function (node, parent) {
   // we're a property key and we aren't computed so we aren't referenced
   if (t.isProperty(parent) && parent.key === node && !parent.computed) return false;
@@ -152,6 +165,12 @@ t.isReferenced = function (node, parent) {
   return false;
 };
 
+t.isValidIdentifier = function (name) {
+  return _.isString(name) && esutils.keyword.isIdentifierName(name) && !esutils.keyword.isKeywordES6(name, true);
+};
+
+//
+
 t.toIdentifier = function (name) {
   if (t.isIdentifier(name)) return name.name;
 
@@ -172,10 +191,6 @@ t.toIdentifier = function (name) {
   return name || '_';
 };
 
-t.isValidIdentifier = function (name) {
-  return _.isString(name) && esutils.keyword.isIdentifierName(name) && !esutils.keyword.isKeywordES6(name, true);
-};
-
 t.ensureBlock = function (node, key) {
   key = key || "body";
   node[key] = t.toBlock(node[key], node);
@@ -234,6 +249,8 @@ t.toBlock = function (node, parent) {
   return t.blockStatement(node);
 };
 
+//
+
 t.getUid = function (parent, file, scope) {
   var node = parent;
 
@@ -327,6 +344,8 @@ t.getIds.arrays = {
   ObjectPattern: ["properties"]
 };
 
+//
+
 t.isLet = function (node) {
   return t.isVariableDeclaration(node) && (node.kind !== "var" || node._let);
 };