diff --git a/tests/gss/check-gssmask.in b/tests/gss/check-gssmask.in
index 0ecb82dab..554a0de7a 100644
--- a/tests/gss/check-gssmask.in
+++ b/tests/gss/check-gssmask.in
@@ -121,6 +121,7 @@ ${gssmaestro} \
     --slaves=localhost:8889 \
     --slaves=localhost:8890 \
     --slaves=localhost:8891 \
+    --wrap-ext \
     --principals=user1@${R}:u1 || exitcode=1
 
 trap "" EXIT