diff --git a/Concurrent Systems/notes/4 - Semaphores.md b/Concurrent Systems/notes/4 - Semaphores.md
index ef5bb33..62e0129 100644
--- a/Concurrent Systems/notes/4 - Semaphores.md	
+++ b/Concurrent Systems/notes/4 - Semaphores.md	
@@ -299,4 +299,5 @@ def end_write() :=
 	W_MUTEX.up()
 	return
 ```
-This is prioritizing writers as if there are writers waiting, they will be waiting at `GLOB_MUTEX.down()`. This semaphore is upped before `PRIO_MUTEX` which is the one that blocks readers.
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+This is prioritizing writers as if there are writers waiting, they will be waiting at `GLOB_MUTEX.down()`. This semaphore is upped before `PRIO_MUTEX` which is the one that blocks readers.
+It is weak as a writer cannot block readers twice.
\ No newline at end of file