diff --git a/scripts/maintainer.requirements.txt b/scripts/maintainer.requirements.txt
index 87341405e..425635474 100644
--- a/scripts/maintainer.requirements.txt
+++ b/scripts/maintainer.requirements.txt
@@ -9,3 +9,6 @@ clang
 # For building some test vectors
 pycryptodomex
 pycryptodome-test-vectors
+
+# For building `tests/data_files/server9-bad-saltlen.crt`
+asn1crypto