diff --git a/common/modules/io.jsm b/common/modules/io.jsm
index b249f22a..ee1f8dbe 100644
--- a/common/modules/io.jsm
+++ b/common/modules/io.jsm
@@ -399,7 +399,7 @@ var IO = Module("io", {
                 dir = this.File(dir, true);
 
                 let file = dir.child(bin);
-                if (file.exists())
+                if (file.exists() && file.isFile() && file.isExecutable())
                     return file;
 
                 // TODO: couldn't we just palm this off to the start command?