diff --git a/lib/iris/cube.py b/lib/iris/cube.py
index 40f5fbcef3..c3f77c9288 100644
--- a/lib/iris/cube.py
+++ b/lib/iris/cube.py
@@ -981,9 +981,7 @@ def convert_units(self, unit):
         celsius and subtract 273.15 from each value in
         :attr:`~iris.cube.Cube.data`.
 
-        .. warning::
-            Calling this method will trigger any deferred loading, causing
-            the cube's data array to be loaded into memory.
+        This operation preserves lazy data.
 
         """
         # If the cube has units convert the data.