diff --git a/scripts/maintainer.requirements.txt b/scripts/maintainer.requirements.txt
index b149921a24..dd28264864 100644
--- a/scripts/maintainer.requirements.txt
+++ b/scripts/maintainer.requirements.txt
@@ -8,3 +8,6 @@ clang
 # For building some test vectors
 pycryptodomex
 pycryptodome-test-vectors
+
+# For building `tests/data_files/server9-bad-saltlen.crt`
+asn1crypto