diff --git a/mad/fact.mad b/mad/fact.mad
index 9ecaa3e..c791644 100644
--- a/mad/fact.mad
+++ b/mad/fact.mad
@@ -1,6 +1,6 @@
 ;; Functions to calculate factorial
 
-;; Recursive version
+;; Recursive version, not tail call optimized
 (def recFact (fn (n) (if (< n 2) 1 (* n (recFact (- n 1))))))
 
 ;; Apply version
diff --git a/mad/fib.mad b/mad/fib.mad
index 2883128..f093016 100644
--- a/mad/fib.mad
+++ b/mad/fib.mad
@@ -6,6 +6,6 @@
 ;; Return the sum of the last 2 numbers in a sequence
 (def sumOfLast (fn (l) (+ (last l) (get l (- (len l) 2)))))
 
-;; Faster version, return vector of n numbers
+;; Faster version, return vector of n numbers, tail call optimized
 (def fibListRec (fn (n l) (if (< (len l) n) (fibListRec n (push l (sumOfLast l))) l)))
 (def fibList (fn (n) (fibListRec n [0 1])))