diff --git a/lisainstrument/containers.py b/lisainstrument/containers.py
index 17de7f8afaecb1b223252976b99c22c712c75cab..0f4437134ef662fa8d5c2ab84ad6df42b94b7c4e 100644
--- a/lisainstrument/containers.py
+++ b/lisainstrument/containers.py
@@ -38,14 +38,6 @@ class ForEachObject(abc.ABC):
         """Return list of object indices."""
         raise NotImplementedError
 
-    def transform(self, transformation):
-        """Transform dictionary on-the-spot.
-
-        Args:
-            transformation: function (mosa, value -> new_value)
-        """
-        self.dict = {mosa: transformation(mosa, self[mosa]) for mosa in self.indices()}
-
     def transformed(self, transformation):
         """Return a new dictionary from transformed objects.