diff --git a/distribution/lib/Standard/Base/0.2.32-SNAPSHOT/src/Data/Vector.enso b/distribution/lib/Standard/Base/0.2.32-SNAPSHOT/src/Data/Vector.enso
index 47f379ffaa..a4fb886244 100644
--- a/distribution/lib/Standard/Base/0.2.32-SNAPSHOT/src/Data/Vector.enso
+++ b/distribution/lib/Standard/Base/0.2.32-SNAPSHOT/src/Data/Vector.enso
@@ -755,6 +755,16 @@ type Vector
              [Pair 1 "a", Pair 2 "b", Pair 1 "c"] . distinct (on = _.first) == [Pair 1 "a", Pair 2 "b"]
     distinct : (Any -> Any) -> Vector Any
     distinct (on = x->x) =
+        ## TODO [JD] This is based on the Map class until a HashMap is available.
+
+           Current implementation allows for a consistent distinct with the Enso `==` operator.
+           Using the Map, is less efficient than a HashMap based as requires searching the tree (O(Log N)).
+           A HashMap would allow for a O(1) operation to confirm if an item has been seen already.
+           There is no native HashMap within Enso at present, and the polyglot approach does not produce
+           consistent results with the `==` operator.
+
+           More details on the HashCode / HashMap ticket https://www.pivotaltracker.com/story/show/181027272.
+
         recovered = Panic.recover
             builder = here.new_builder
             this.fold Map.empty existing->