--- a/hgext/convert/cvs.py	Sun Oct 28 09:47:54 2007 +0100
+++ b/hgext/convert/cvs.py	Tue Oct 30 22:14:15 2007 +0100
@@ -3,7 +3,7 @@
 import os, locale, re, socket
 from mercurial import util
 
-from common import NoRepo, commit, converter_source
+from common import NoRepo, commit, converter_source, checktool
 
 class convert_cvs(converter_source):
     def __init__(self, ui, path, rev=None):
@@ -13,6 +13,9 @@
         if not os.path.exists(cvs):
             raise NoRepo("couldn't open CVS repo %s" % path)
 
+        for tool in ('cvsps', 'cvs'):
+            checktool(tool)
+
         self.changeset = {}
         self.files = {}
         self.tags = {}