diff --git a/include/lib/aarch64/arch_helpers.h b/include/lib/aarch64/arch_helpers.h
index b880497..03110fd 100644
--- a/include/lib/aarch64/arch_helpers.h
+++ b/include/lib/aarch64/arch_helpers.h
@@ -204,6 +204,7 @@
 DEFINE_SYSOP_TYPE_FUNC(dsb, ish)
 DEFINE_SYSOP_TYPE_FUNC(dsb, ishst)
 DEFINE_SYSOP_TYPE_FUNC(dmb, ish)
+DEFINE_SYSOP_TYPE_FUNC(dmb, ishst)
 DEFINE_SYSOP_FUNC(isb)
 
 uint32_t get_afflvl_shift(uint32_t);