diff --git a/book/source/11-decryption.md b/book/source/11-decryption.md
index 31ee3ea..fdfa4ba 100644
--- a/book/source/11-decryption.md
+++ b/book/source/11-decryption.md
@@ -142,7 +142,7 @@ Since SEIPD version 1 is susceptible to downgrade attacks under certain scenario
 To decrypt the contents of a version 1 SEIPD packet, the session-key obtained in the previous step is used.
 The cipher algorithm is determined by TODO.
 
-```{adminonition} TODO
+```{admonition} TODO
 :class: warning
 
 Describe in detail, how the cipher algorithm is obtained.