diff --git a/tests/spread/smoketests/basic/charmcraft-platforms-24.04.yaml b/tests/spread/smoketests/basic/charmcraft-platforms-24.04.yaml
index d75f0eeef..1a0720c8d 100644
--- a/tests/spread/smoketests/basic/charmcraft-platforms-24.04.yaml
+++ b/tests/spread/smoketests/basic/charmcraft-platforms-24.04.yaml
@@ -9,6 +9,9 @@ platforms:
   amd64:
   arm64:
   riscv64:
+  mainframe:
+    build-on: [amd64, arm64]
+    build-for: [s390x]
 parts:
   my-charm:
     plugin: charm