diff --git a/pykat/finesse.py b/pykat/finesse.py
index c545945354dfefac0433f20687e161ba94e92d70..96d7af9fcd00ca1e769c369d7580ea0698972e48 100644
--- a/pykat/finesse.py
+++ b/pykat/finesse.py
@@ -1208,7 +1208,7 @@ class kat(object):
         as just a string. This of course can create possible conflicts with other
         pykat object that create similar commands so becareful.
         """
-        self.__blocks[key].contents.append(line)
+        self.__blocks[block].contents.append(line)
                         
     def generateKatScript(self) :
         """ Generates the kat file which can then be run """