--- a/buttercup/checkout.py	Tue Dec 28 16:52:26 2010 -0800
+++ b/buttercup/checkout.py	Mon May 30 13:40:13 2011 -0700
@@ -60,13 +60,13 @@
         sys.exit(0)
 
     # setup the src directory in a virtualenv
-    assert 'VIRTUAL_ENV' in os.environ
+    assert 'VIRTUAL_ENV' in os.environ, "You must have a virtualenv activated"
     src = os.path.join(os.environ['VIRTUAL_ENV'], 'src')
     if not os.path.exists(src):
         os.mkdir(src)
     os.chdir(src)
 
-    # clone othe sources
+    # clone the sources
     for source in sources:
         if os.path.exists(source[0]):
             if options.update: