diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index b6f7655..b7fb173 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -234,3 +234,8 @@
 endif
 
 SANITIZE_UB := off
+
+# For ARMv8.1 (AArch64) platforms, enabling this option selects the spinlock
+# implementation variant using the ARMv8.1-LSE compare-and-swap instruction.
+# Default: disabled
+USE_SPINLOCK_CAS := 0