diff --git a/lib/6to5/transformation/transformers/spec-member-expression-literals.js b/lib/6to5/transformation/transformers/spec-member-expression-literals.js
index d1c58414d7..6803865073 100644
--- a/lib/6to5/transformation/transformers/spec-member-expression-literals.js
+++ b/lib/6to5/transformation/transformers/spec-member-expression-literals.js
@@ -1,5 +1,4 @@
-var esutils = require("esutils");
-var t       = require("../../types");
+var t = require("../../types");
 
 exports.MemberExpression = function (node) {
   var prop = node.property;
@@ -7,7 +6,7 @@ exports.MemberExpression = function (node) {
     // computed literal that is a valid identifier
     node.property = t.identifier(prop.value);
     node.computed = false;
-  } else if (!node.computed && t.isIdentifier(prop) && esutils.keyword.isKeywordES6(prop.name, true)) {
+  } else if (!node.computed && t.isIdentifier(prop) && !t.isValidIdentifier(prop.name)) {
     node.property = t.literal(prop.name);
     node.computed = true;
   }
diff --git a/lib/6to5/transformation/transformers/spec-property-literals.js b/lib/6to5/transformation/transformers/spec-property-literals.js
index dff7244d1d..f750fa7527 100644
--- a/lib/6to5/transformation/transformers/spec-property-literals.js
+++ b/lib/6to5/transformation/transformers/spec-property-literals.js
@@ -1,5 +1,4 @@
-var esutils = require("esutils");
-var t       = require("../../types");
+var t = require("../../types");
 
 exports.Property = function (node) {
   var key = node.key;
@@ -7,7 +6,7 @@ exports.Property = function (node) {
     // property key is a literal but a valid identifier
     node.key = t.identifier(key.value);
     node.computed = false;
-  } else if (!node.computed && t.isIdentifier(key) && esutils.keyword.isKeywordES6(key.name, true)) {
+  } else if (!node.computed && t.isIdentifier(key) && !t.isValidIdentifier(key.name)) {
     // property key is a keyword
     node.key = t.literal(key.name);
   }