diff --git a/arch/AArch64.S b/arch/AArch64.S
index c7d7f4f..71f2b89 100644
--- a/arch/AArch64.S
+++ b/arch/AArch64.S
@@ -175,7 +175,23 @@ cu_memtest:
     ret
 
 cu_va_start:
+    stp xzr, x1, [x0], #16
+    stp x2,  x3, [x0], #16
+    stp x4,  x5, [x0], #16
+    stp x6,  x7, [x0], #16
     ret
 
 cu_va_arg:
+    // x0 - va_list, x1 - index
+    mov x1, x1, lsl #3
+    cmp x1, #56
+    bgt .va_stack
+
+    add x0, x0, x1
+    ldr x0, [x0]
+    ret
+.va_stack:
+    sub x1, x1, #48
+    add x0, sp, x1
+    ldr x0, [x0]
     ret
diff --git a/va_list.h b/va_list.h
index 23a1249..416761a 100644
--- a/va_list.h
+++ b/va_list.h
@@ -5,7 +5,9 @@
 
 #if (CU_ARCH == x86_64)
 #   define VA_NUM   6
-#else
+#elif (CU_ARCH == AARCH64)
+#   define VA_NUM   8
+#elif
 #   define VA_NUM   0
 #endif