diff --git a/packages/babel-traverse/src/index.js b/packages/babel-traverse/src/index.js
index 01a48112c4d9..099e6f0bf7d9 100644
--- a/packages/babel-traverse/src/index.js
+++ b/packages/babel-traverse/src/index.js
@@ -9,6 +9,7 @@ import * as t from "babel-types";
 export { default as NodePath } from "./path";
 export { default as Scope } from "./scope";
 export { default as Hub } from "./hub";
+export { default as cache } from "./path/cache";
 export { visitors };
 
 export default function traverse(
diff --git a/packages/babel-traverse/src/path/cache.js b/packages/babel-traverse/src/path/cache.js
new file mode 100644
index 000000000000..a58ecc5f08de
--- /dev/null
+++ b/packages/babel-traverse/src/path/cache.js
@@ -0,0 +1,25 @@
+let wm = new WeakMap();
+
+// To implement clear we need to export a facade.
+export default {
+  clear() {
+    wm = new WeakMap();
+  },
+
+  delete(k) {
+    return wm.delete(k)
+  },
+
+  get(k) {
+    return wm.get(k)
+  },
+
+  has(k) {
+    return wm.has(k)
+  },
+
+  set(k, v) {
+    wm.set(k, v);
+    return wm;
+  },
+};
diff --git a/packages/babel-traverse/src/path/constants.js b/packages/babel-traverse/src/path/constants.js
deleted file mode 100644
index 11431edfe431..000000000000
--- a/packages/babel-traverse/src/path/constants.js
+++ /dev/null
@@ -1 +0,0 @@
-export const PATH_CACHE_KEY = "_paths"; //Symbol();
diff --git a/packages/babel-traverse/src/path/index.js b/packages/babel-traverse/src/path/index.js
index 4fa06c9b3033..fadb928ab6ae 100644
--- a/packages/babel-traverse/src/path/index.js
+++ b/packages/babel-traverse/src/path/index.js
@@ -4,12 +4,12 @@ import type Hub from "../hub";
 import type TraversalContext from "../context";
 import * as virtualTypes from "./lib/virtual-types";
 import buildDebug from "debug";
-import { PATH_CACHE_KEY } from "./constants";
 import invariant from "invariant";
 import traverse from "../index";
 import assign from "lodash/object/assign";
 import Scope from "../scope";
 import * as t from "babel-types";
+import cache from "./cache";
 
 let debug = buildDebug("babel");
 
@@ -69,7 +69,11 @@ export default class NodePath {
 
     let targetNode = container[key];
 
-    let paths = parent[PATH_CACHE_KEY] = parent[PATH_CACHE_KEY] || [];
+    let paths = cache.get(parent) || [];
+    if (!cache.has(parent)) {
+      cache.set(parent, paths);
+    }
+
     let path;
 
     for (let i = 0; i < paths.length; i++) {
diff --git a/packages/babel-traverse/src/path/modification.js b/packages/babel-traverse/src/path/modification.js
index b2827613a3ac..c32745bb9c3a 100644
--- a/packages/babel-traverse/src/path/modification.js
+++ b/packages/babel-traverse/src/path/modification.js
@@ -1,7 +1,7 @@
 /* eslint max-len: 0 */
 // This file contains methods that modify the path/node in some ways.
 
-import { PATH_CACHE_KEY } from "./constants";
+import cache from "./cache";
 import PathHoister from "./lib/hoister";
 import NodePath from "./index";
 import * as t from "babel-types";
@@ -136,7 +136,7 @@ export function insertAfter(nodes) {
 export function updateSiblingKeys(fromIndex, incrementBy) {
   if (!this.parent) return;
 
-  let paths = this.parent[PATH_CACHE_KEY];
+  let paths = cache.get(this.parent);
   for (let i = 0; i < paths.length; i++) {
     let path = paths[i];
     if (path.key >= fromIndex) {