diff --git a/requests/exceptions.py b/requests/exceptions.py
index 63f2c9ce..22207e35 100644
--- a/requests/exceptions.py
+++ b/requests/exceptions.py
@@ -9,7 +9,7 @@ This module contains the set of Requests' exceptions.
 """
 
 
-class RequestException(RuntimeError):
+class RequestException(IOError):
     """There was an ambiguous exception that occurred while handling your
     request."""