diff --git a/TODO.md b/TODO.md
index 5f8e9c61..8c52c797 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,4 @@
 # Compiler 
-  - Add constraints for struct constructor arguments based on the types in the struct
   - Can't have star in function name when baking
   - Don't apply borrowing rules to primitive (auto-copyable) types like int/float/bool/char
   - Compile struct member lookups properly
@@ -24,6 +23,7 @@
   - Avoid problems with name shadowing when freeing a local variable (is this possible? disallow shadowing instead?)
   - deftype (tagged unions)
   - Clean up the awful 'list-to-ast' function
+  - Complete type constraints for binops, check for "numeric" types
 
 # Lisp Core Libs
   - assert-eq shows wrong result when the assertion fails? (in ffi situations, the wrong type is produced and compared to something else)
diff --git a/lisp/infer_types.carp b/lisp/infer_types.carp
index 542849cd..7ce32464 100644
--- a/lisp/infer_types.carp
+++ b/lisp/infer_types.carp
@@ -59,10 +59,6 @@
 
       :app (let [ret-constr {:a  (get ast :type) :b (get-in ast '(:head :type 2)) :doc "ret-constr for :app"}
                  arg-constrs (map2 (fn (a b) {:a a :b b :doc "app-arg"}) (get-in ast '(:head :type 1)) (map :type (:tail ast)))
-                 ;; func-constrs (let [app-f-sym (get-in ast '(:head :value))
-                 ;;                    app-f-name (str app-f-sym)
-                 ;;                    app-f (eval app-f-sym)]
-                 ;;                )
                  head-constrs (generate-constraints-internal '() (:head ast) type-env)
                  tail-constrs (reduce (fn (constrs tail-form) (generate-constraints-internal constrs tail-form type-env))
                                       '() (:tail ast))
@@ -91,7 +87,12 @@
       :lookup (if (has-key? ast :self-recursive)
                 constraints
                 (if (has-key? ast :constructor)
-                  constraints ;; TODO: what's the correct thing to do here?
+                  (let [member-types (array-to-list (:member-types ast))
+                        t (:type ast)
+                        constructor-arg-constrs (map2 (fn [a b] {:a a :b b :doc "constructor-arg"})
+                                                      member-types
+                                                      (nth t 1))]
+                    constructor-arg-constrs)
                   (let [val (:value ast)
                         ;;_ (println (str "not self-recursive: \n" ast))
                         t (get-type-of-symbol type-env val)
diff --git a/out/project.carp b/out/project.carp
index 99a070fb..36cc7286 100644
--- a/out/project.carp
+++ b/out/project.carp
@@ -117,3 +117,9 @@
 
 (defn trixy-5 []
   (println (ref (str (ref (color 2.3))))))
+
+(defn trixy-6 [x y z]
+  (Color x y z))
+
+(def ast6 (lambda-to-ast (code trixy-6)))
+(def asta6 (annotate-ast ast6))