diff --git a/packages/babel-plugin-transform-es2015-parameters/src/rest.js b/packages/babel-plugin-transform-es2015-parameters/src/rest.js
index 70b3666770..bda77d8c11 100644
--- a/packages/babel-plugin-transform-es2015-parameters/src/rest.js
+++ b/packages/babel-plugin-transform-es2015-parameters/src/rest.js
@@ -69,6 +69,11 @@ let memberExpressionOptimisationVisitor = {
     } else {
       let {parentPath} = path;
 
+      // Is this identifier the right hand side of a default parameter?
+      if (parentPath.listKey === "params" && parentPath.key < state.offset) {
+        return;
+      }
+
       // ex: `args[0]`
       // ex: `args.whatever`
       if (parentPath.isMemberExpression({ object: node })) {
diff --git a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/actual.js b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/actual.js
new file mode 100644
index 0000000000..1f3eeb12c8
--- /dev/null
+++ b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/actual.js
@@ -0,0 +1,15 @@
+const a = 1;
+function rest(b = a, ...a) {
+  assert.equal(b, 1);
+}
+rest(undefined, 2)
+
+function rest2(b = a, ...a) {
+  assert.equal(a[0], 2);
+}
+rest2(undefined, 2)
+
+function rest3(b = a, ...a) {
+  assert.equal(a.length, 1);
+}
+rest3(undefined, 2)
diff --git a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/exec.js b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/exec.js
new file mode 100644
index 0000000000..1f3eeb12c8
--- /dev/null
+++ b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/exec.js
@@ -0,0 +1,15 @@
+const a = 1;
+function rest(b = a, ...a) {
+  assert.equal(b, 1);
+}
+rest(undefined, 2)
+
+function rest2(b = a, ...a) {
+  assert.equal(a[0], 2);
+}
+rest2(undefined, 2)
+
+function rest3(b = a, ...a) {
+  assert.equal(a.length, 1);
+}
+rest3(undefined, 2)
diff --git a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/expected.js b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/expected.js
new file mode 100644
index 0000000000..f74dcedeed
--- /dev/null
+++ b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/default-rest/expected.js
@@ -0,0 +1,21 @@
+var a = 1;
+function rest() {
+  var b = arguments.length <= 0 || arguments[0] === undefined ? a : arguments[0];
+
+  assert.equal(b, 1);
+}
+rest(undefined, 2);
+
+function rest2() {
+  var b = arguments.length <= 0 || arguments[0] === undefined ? a : arguments[0];
+
+  assert.equal(arguments.length <= 1 ? undefined : arguments[1], 2);
+}
+rest2(undefined, 2);
+
+function rest3() {
+  var b = arguments.length <= 0 || arguments[0] === undefined ? a : arguments[0];
+
+  assert.equal(arguments.length - 1, 1);
+}
+rest3(undefined, 2);