diff --git a/SyncPrim/sync-4.md b/SyncPrim/sync-4.md
index bd1a05b..c37fa93 100644
--- a/SyncPrim/sync-4.md
+++ b/SyncPrim/sync-4.md
@@ -10,7 +10,7 @@ As in all previous parts of this [book](https://0xax.gitbooks.io/linux-insides/c
 
 So, let's start.
 
-Mutexes
+Concept of `mutex`
 --------------------------------------------------------------------------------
 
 We already familiar with the [semaphore](https://en.wikipedia.org/wiki/Semaphore_%28programming%29) synchronization primitive from the previous [part]((https://0xax.gitbooks.io/linux-insides/content/SyncPrim/sync-4.html). It represented by the: