diff --git a/setup.py b/setup.py
index 3f1a9a00..c8d48eb7 100644
--- a/setup.py
+++ b/setup.py
@@ -137,9 +137,12 @@ class CustomInstall(install):
                 os.symlink(source, dest)
 
     def run(self):
-        ignore_idx = 0 if self.root is None else len(self.root)
-        if self.root[-1] == '/':
-            ignore_idx-=1 # we dont want to remove the first '/' in _final paths
+        if not self.root:
+            ignore_idx = 0
+        else:
+            ignore_idx = len(self.root)
+            if self.root[-1] == '/':
+                ignore_idx-=1 # we dont want to remove the first '/' in _final paths
         # _final suffixed attributes are the ones without the self.root prefix path
         # it's used at least on Arch linux installation as install is made on a local $pkgdir
         # which is later moved to user's FS root