diff --git a/kioss/_plan.py b/kioss/_plan.py
index 3bfa601..f6ce02f 100644
--- a/kioss/_plan.py
+++ b/kioss/_plan.py
@@ -17,7 +17,6 @@
 
 T = TypeVar("T")
 R = TypeVar("R")
-Source = Callable[[], Iterator[T]]
 
 
 class APipe(Iterable[T], ABC):