diff --git a/Lib/site.py b/Lib/site.py
index 13522b1..cc6dd39 100644
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -177,7 +177,7 @@
             # locations. Currently only per-user, but /Library and
             # /Network/Library could be added too
             if 'Python.framework' in prefix:
-                home = os.environ['HOME']
+                home = os.environ.get('HOME')
                 if home:
                     sitedirs.append(
                         os.path.join(home,