diff --git a/src/extensions/default/OpenWithExternalApplication/main.js b/src/extensions/default/OpenWithExternalApplication/main.js
index f9151b42d7d..71ddd0db166 100644
--- a/src/extensions/default/OpenWithExternalApplication/main.js
+++ b/src/extensions/default/OpenWithExternalApplication/main.js
@@ -49,7 +49,7 @@ define(function (require, exports, module) {
     var extensionToExtApplicationMap = {};
 
     function convertUnixPathToWindowsPath(path) {
-        if (brackets.platform === "win") {
+        if (brackets.platform === "win" && path && path.charAt(0).isAlpha()) {
             path = path.split("/").join("\\");
         }
         return path;