diff --git a/docs/src/basics/integrator.md b/docs/src/basics/integrator.md
index 4b1e501c8c..75e67770ac 100644
--- a/docs/src/basics/integrator.md
+++ b/docs/src/basics/integrator.md
@@ -224,6 +224,7 @@ will run the auto `dt` initialization algorithm.
 ### Misc
 
 * `get_du(integrator)`: Returns the derivative at `t`.
+* `get_du!(out,integrator)`: Write the current derivative at `t` into `out`.
 
 #### Note