diff --git a/lib/sinon/util/core/is-restorable.js b/lib/sinon/util/core/is-restorable.js
new file mode 100644
index 000000000..4fc3a9f2e
--- /dev/null
+++ b/lib/sinon/util/core/is-restorable.js
@@ -0,0 +1,7 @@
+"use strict";
+
+function isRestorable(obj) {
+    return typeof obj === "function" && typeof obj.restore === "function" && obj.restore.sinon;
+}
+
+module.exports = isRestorable;
diff --git a/lib/sinon/util/core/restore.js b/lib/sinon/util/core/restore.js
index 3e4abeb21..4ea4a73ed 100644
--- a/lib/sinon/util/core/restore.js
+++ b/lib/sinon/util/core/restore.js
@@ -1,11 +1,8 @@
 "use strict";
 
+var isRestorable = require("./is-restorable");
 var walk = require("./walk");
 
-function isRestorable(obj) {
-    return typeof obj === "function" && typeof obj.restore === "function" && obj.restore.sinon;
-}
-
 module.exports = function restore(object) {
     if (object !== null && typeof object === "object") {
         walk(object, function (prop) {