diff --git a/lightening/aarch64.h b/lightening/aarch64.h
index 0e675a9ee..9aa0f0dca 100644
--- a/lightening/aarch64.h
+++ b/lightening/aarch64.h
@@ -105,9 +105,9 @@
 #define JIT_R13   _X13
 #define JIT_R14   _X14
 #define JIT_R15   _X15
-#define JIT_R16   _X16
-#define JIT_TMP0  _X17
-#define JIT_TMP1  _X18
+#define JIT_TMP0  _X16
+#define JIT_TMP1  _X17
+// x18 is reserved by the platform.
 #define JIT_V0    _X19
 #define JIT_V1    _X20
 #define JIT_V2    _X21