diff --git a/docs/lectures/osc/04_concurrency1.md b/docs/lectures/osc/04_concurrency1.md
index 3473d7c..b6241f5 100644
--- a/docs/lectures/osc/04_concurrency1.md
+++ b/docs/lectures/osc/04_concurrency1.md
@@ -144,7 +144,7 @@ These requirements have to be satisfied, independent of the order in which seque
 
 ### Enforcing Mutual Exclusion
 
-**Approaches** for mutual exclusion can be
+**Approaches** for mutual exclusion can be:
 
 1. Software based - Peterson's solution
 2. Hardware based - `test_and_set()` `swap_and_comapare()`