diff --git a/IPython/frontend/_process/killableprocess.py b/IPython/frontend/_process/killableprocess.py
index 86fbc6f..955482c 100644
--- a/IPython/frontend/_process/killableprocess.py
+++ b/IPython/frontend/_process/killableprocess.py
@@ -73,6 +73,8 @@ skip = False
 if mswindows:
     import platform
     if platform.uname()[3] == '' or platform.uname()[3] > '6.0.6000':
+        # Killable process does not work under vista when starting for
+        # something else than cmd.
         skip = True
     else:
         import winprocess