diff --git a/src/boot/boot.janet b/src/boot/boot.janet
index 1b834cf8..66038192 100644
--- a/src/boot/boot.janet
+++ b/src/boot/boot.janet
@@ -914,8 +914,9 @@
   res)
 
 (defn update
-  "Accepts a key argument and passes its' associated value to a function.
-  The key then, is associated to the function's return value"
+  "Accepts a key argument and passes its associated value to a function.
+  The key is the re-associated to the function's return value. Returns the updated
+  data structure ds."
   [ds key func & args]
   (def old (get ds key))
   (set (ds key) (func old ;args)))