diff --git a/target-s390x/helper.h b/target-s390x/helper.h
index f5dabb7..dea7071 100644
--- a/target-s390x/helper.h
+++ b/target-s390x/helper.h
@@ -110,7 +110,7 @@
 DEF_HELPER_4(mvcs, i32, env, i64, i64, i64)
 DEF_HELPER_4(mvcp, i32, env, i64, i64, i64)
 DEF_HELPER_4(sigp, i32, env, i64, i32, i64)
-DEF_HELPER_2(sacf, void, env, i64)
+DEF_HELPER_FLAGS_2(sacf, TCG_CALL_NO_WG, void, env, i64)
 DEF_HELPER_FLAGS_3(ipte, TCG_CALL_NO_RWG, void, env, i64, i64)
 DEF_HELPER_FLAGS_1(ptlb, TCG_CALL_NO_RWG, void, env)
 DEF_HELPER_2(lra, i64, env, i64)