diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/class-argument-scope/example/exec.js b/packages/babel-plugin-transform-regenerator/test/fixtures/class-argument-scope/example/exec.js
new file mode 100644
index 0000000000..46f1fd4f74
--- /dev/null
+++ b/packages/babel-plugin-transform-regenerator/test/fixtures/class-argument-scope/example/exec.js
@@ -0,0 +1,8 @@
+class Test {
+  *iter(arg = this) {
+    yield arg;
+  }
+}
+
+let test = new Test;
+assert.equal(test.iter().next().value, test);
diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/class-argument-scope/options.json b/packages/babel-plugin-transform-regenerator/test/fixtures/class-argument-scope/options.json
new file mode 100644
index 0000000000..3c078e9f99
--- /dev/null
+++ b/packages/babel-plugin-transform-regenerator/test/fixtures/class-argument-scope/options.json
@@ -0,0 +1,5 @@
+{
+  "presets": [
+    "es2015"
+  ]
+}
diff --git a/packages/babel-traverse/src/context.js b/packages/babel-traverse/src/context.js
index 2e134f0abe..edad4ea598 100644
--- a/packages/babel-traverse/src/context.js
+++ b/packages/babel-traverse/src/context.js
@@ -105,6 +105,9 @@ export default class TraversalContext {
       path.resync();
       path.pushContext(this);
 
+      // this path no longer belongs to the tree
+      if (path.key === null) continue;
+
       if (testing && queue.length >= 1000) {
         this.trap = true;
       }