diff --git a/tools/files.js b/tools/files.js
index 89ef757614..2eb6368fb4 100644
--- a/tools/files.js
+++ b/tools/files.js
@@ -1175,7 +1175,7 @@ var toPosixPath = function (p, notAbsolute) {
 
 var toDosPath = function (p, notAbsolute) {
   if (p[0] === '/' && ! notAbsolute) {
-    if (! /^\/[A-Za-z]\//.test(p))
+    if (! /^\/[A-Za-z](\/|$)/.test(p))
       throw new Error("Surprising path: " + p);
     // transform a previously windows path back
     // "/C/something" to "c:/something"