diff --git a/src/crypto/crypto_openssl.c b/src/crypto/crypto_openssl.c
index 1b0c1ec96..23ae5462d 100644
--- a/src/crypto/crypto_openssl.c
+++ b/src/crypto/crypto_openssl.c
@@ -1295,7 +1295,13 @@ void crypto_bignum_deinit(struct crypto_bignum *n, int clear)
 int crypto_bignum_to_bin(const struct crypto_bignum *a,
 			 u8 *buf, size_t buflen, size_t padlen)
 {
+#ifdef OPENSSL_IS_BORINGSSL
+#else /* OPENSSL_IS_BORINGSSL */
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER)
+#else
 	int num_bytes, offset;
+#endif
+#endif /* OPENSSL_IS_BORINGSSL */
 
 	if (TEST_FAIL())
 		return -1;
@@ -1303,6 +1309,14 @@ int crypto_bignum_to_bin(const struct crypto_bignum *a,
 	if (padlen > buflen)
 		return -1;
 
+#ifdef OPENSSL_IS_BORINGSSL
+	if (BN_bn2bin_padded(buf, padlen, (const BIGNUM *) a) == 0)
+		return -1;
+	return padlen;
+#else /* OPENSSL_IS_BORINGSSL */
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER)
+	return BN_bn2binpad((const BIGNUM *) a, buf, padlen);
+#else
 	num_bytes = BN_num_bytes((const BIGNUM *) a);
 	if ((size_t) num_bytes > buflen)
 		return -1;
@@ -1315,6 +1329,8 @@ int crypto_bignum_to_bin(const struct crypto_bignum *a,
 	BN_bn2bin((const BIGNUM *) a, buf + offset);
 
 	return num_bytes + offset;
+#endif
+#endif /* OPENSSL_IS_BORINGSSL */
 }