diff --git a/net/wireguard/noise.c b/net/wireguard/noise.c
index 4405125..2e572b2 100644
--- a/src/noise.c
+++ b/src/noise.c
@@ -17,6 +17,8 @@
 #include <linux/highmem.h>
 #include <crypto/algapi.h>

+#define ALIGN_DOWN(value, align) ((value) & ~((align) - 1))
+
 /* This implements Noise_IKpsk2:
  *
  * <- s