diff --git a/Concurrent Systems/notes/5 - Software Transactional Memory.md b/Concurrent Systems/notes/5 - Software Transactional Memory.md
index 4cabc7f..45e7603 100644
--- a/Concurrent Systems/notes/5 - Software Transactional Memory.md	
+++ b/Concurrent Systems/notes/5 - Software Transactional Memory.md	
@@ -64,7 +64,7 @@ begin_T() :=
 	birthdate(T) <- CLOCK + 1
 
 X.read_T() :=
-	if l?(XX) != ⊥ then
+	if lc(XX) != ⊥ then
 		return lc(XX).val
 	lc(XX) <- XX
 	if lc(XX).date >= birthdate(T) then