diff --git a/janet/validate.janet b/janet/validate.janet
index 2b09693..1113699 100644
--- a/janet/validate.janet
+++ b/janet/validate.janet
@@ -13,5 +13,8 @@ Tracking here, before I start writing this code, the kinds of validation we're h
 * first-level property access with pkg, e.g. `Foo :bar`--bar must be on Foo
 * recur in tail position in `loop` forms
 * recur not called outside of `loop` forms
+* arity checking where possible
+ - loop forms
+ - try to resolve function name, if you can, check arity of call
 
 )