diff --git a/Lib/netrc.py b/Lib/netrc.py
index 3f1c7c3c4c7..b78d4d83e5b 100644
--- a/Lib/netrc.py
+++ b/Lib/netrc.py
@@ -22,7 +22,10 @@ def __str__(self):
 class netrc:
     def __init__(self, file=None):
         if not file:
-            file = os.path.join(os.environ['HOME'], ".netrc")
+            try:
+                file = os.path.join(os.environ['HOME'], ".netrc")
+            except KeyError:
+                raise IOError("Could not find .netrc: $HOME is not set")
         fp = open(file)
         self.hosts = {}
         self.macros = {}