diff --git a/lib/6to5/transformation/transformers/destructuring.js b/lib/6to5/transformation/transformers/destructuring.js
index 8522df8b1b..67690661e5 100644
--- a/lib/6to5/transformation/transformers/destructuring.js
+++ b/lib/6to5/transformation/transformers/destructuring.js
@@ -11,21 +11,7 @@ var buildVariableAssign = function (kind, id, init) {
   }
 };
 
-var normalise = function (node) {
-  if (t.isParenthesizedExpression(node)) {
-    return node.expression;
-  } else {
-    return node;
-  }
-};
-
-var isPattern = function (node) {
-  return t.isPattern(normalise(node));
-};
-
 var push = function (kind, nodes, elem, parentId) {
-  elem = normalise(elem);
-
   if (t.isObjectPattern(elem)) {
     pushObjectPattern(kind, nodes, elem, parentId);
   } else if (t.isArrayPattern(elem)) {
@@ -42,7 +28,7 @@ var pushObjectPattern = function (kind, nodes, pattern, parentId) {
     var pattern2   = prop.value;
     var patternId2 = t.memberExpression(parentId, prop.key);
 
-    if (isPattern(pattern2)) {
+    if (t.isPattern(pattern2)) {
       push(kind, nodes, pattern2, patternId2);
     } else {
       nodes.push(buildVariableAssign(kind, pattern2, patternId2));
@@ -94,7 +80,7 @@ exports.ForOfStatement = function (node, parent, file, scope) {
   if (!t.isVariableDeclaration(declar)) return;
 
   var pattern = declar.declarations[0].id;
-  if (!isPattern(pattern)) return;
+  if (!t.isPattern(pattern)) return;
 
   var key = t.identifier(file.generateUid("ref", scope));
   node.left = t.variableDeclaration(declar.kind, [
@@ -117,7 +103,7 @@ exports.Function = function (node, parent, file, scope) {
   var hasDestructuring = false;
 
   node.params = node.params.map(function (pattern) {
-    if (!isPattern(pattern)) return pattern;
+    if (!t.isPattern(pattern)) return pattern;
 
     hasDestructuring = true;
     var parentId = t.identifier(file.generateUid("ref", scope));
@@ -146,7 +132,7 @@ exports.ExpressionStatement = function (node, parent, file, scope) {
   var expr = node.expression;
   if (expr.type !== "AssignmentExpression") return;
 
-  if (!isPattern(expr.left)) return;
+  if (!t.isPattern(expr.left)) return;
 
   var nodes = [];
 
@@ -167,7 +153,7 @@ exports.VariableDeclaration = function (node, parent, file, scope) {
 
   var hasPattern = false;
   _.each(node.declarations, function (declar) {
-    if (isPattern(declar.id)) {
+    if (t.isPattern(declar.id)) {
       hasPattern = true;
       return false;
     }
diff --git a/package.json b/package.json
index 65030d52d4..45a8f3c221 100644
--- a/package.json
+++ b/package.json
@@ -48,7 +48,7 @@
     "chokidar": "0.10.5",
     "source-map-support": "0.2.8",
     "esutils": "1.1.4",
-    "acorn-6to5": "https://github.com/6to5/acorn-6to5/archive/f5110383517eef0bea78c2da2a1fb01fbed74e4e.tar.gz",
+    "acorn-6to5": "https://github.com/6to5/acorn-6to5/archive/49e421660af161af0e75c2fa066ea356d6650e69.tar.gz",
     "estraverse": "^1.7.0"
   },
   "devDependencies": {
diff --git a/test/fixtures/transformation/destructuring/assignment/actual.js b/test/fixtures/transformation/destructuring/assignment/actual.js
index 653338ee9a..d14ce7e47d 100644
--- a/test/fixtures/transformation/destructuring/assignment/actual.js
+++ b/test/fixtures/transformation/destructuring/assignment/actual.js
@@ -1,2 +1 @@
 [a, b] = f();
-({ x }) = e();
diff --git a/test/fixtures/transformation/destructuring/assignment/expected.js b/test/fixtures/transformation/destructuring/assignment/expected.js
index eda9b31d15..792c6693a2 100644
--- a/test/fixtures/transformation/destructuring/assignment/expected.js
+++ b/test/fixtures/transformation/destructuring/assignment/expected.js
@@ -4,6 +4,3 @@ var _ref = f();
 
 a = _ref[0];
 b = _ref[1];
-var _ref2 = e();
-
-x = _ref2.x;