diff --git a/exam/ex.tex b/exam/ex.tex
index 0382480..d27b98d 100644
--- a/exam/ex.tex
+++ b/exam/ex.tex
@@ -319,7 +319,7 @@
     and simulated transcripts are the same. A given valid transcript occurs with
     probability $1/2^{130}$.
 
-    \item $\mathsf{ID}_{CGI2}$ can be used for authentication if a client
+    \item $\mathsf{ID}_{\mathrm{CGI2}}$ can be used for authentication if a client
       (prover) proves to a server (verifier) the possession of a password
       without actually revealing it. The client shares a commitment with the
       server and as soon as the client wants to log-in, it receives a challenge