diff --git a/crypto/adiantum.c b/crypto/adiantum.c
index a6bca877c3c7..0803451fdbb7 100644
--- a/crypto/adiantum.c
+++ b/crypto/adiantum.c
@@ -350,6 +350,7 @@ static int adiantum_crypt(struct skcipher_request *req, bool enc)
 	if (req->cryptlen < BLOCKCIPHER_BLOCK_SIZE)
 		return -EINVAL;
 
+	memset(&rctx->rbuf.bignum, 0, sizeof(rctx->rbuf.bignum));
 	rctx->enc = enc;
 
 	/*