diff --git a/germinate/germinator.py b/germinate/germinator.py
index a86c25d..57b33bf 100644
--- a/germinate/germinator.py
+++ b/germinate/germinator.py
@@ -1570,7 +1570,7 @@ class Germinator(object):
         #     [[('pkg', '1', '=')]]
         # We thus unpack the first listed alternative pkg-name, for
         # each built-using source.
-        built_using = [i[0][0] for i in self._packages[pkg]["Built-Using"]]
+        built_using = [i[0][0] for i in self._packages[pkg].get("Built-Using", [])]
         pkg_srcs = []
 
         if second_class: