diff --git a/pisi/config.py b/pisi/config.py
index 2962d910..131b1f7d 100644
--- a/pisi/config.py
+++ b/pisi/config.py
@@ -101,7 +101,10 @@ class Config(object):
 
     def tmp_dir(self):
         sysdir = self.subdir(self.values.dirs.tmp_dir)
-        userdir = '/tmp/pisi-' + os.environ['USER'] # FIXME: too unix specific?
+        if os.environ.has_key('USER'):
+            userdir = '/tmp/pisi-' + os.environ['USER']
+        else:
+            userdir = '/tmp/pisi-root'
         # check write access
         if os.access(sysdir, os.W_OK):
             return sysdir