diff --git a/bip39.c b/bip39.c
index df12bcec0..7392d9f2e 100644
--- a/bip39.c
+++ b/bip39.c
@@ -28,6 +28,10 @@ const char *mnemonic_from_data(const uint8_t *data, int len)
 	static char bits[256 + 8];
 	static char mnemo[24 * 10];
 
+	if (len % 4 || len < 16 || len > 32) {
+		return 0;
+	}
+
 	SHA256_Raw((const uint8_t *)data, len, hash);
 
 	for (i = 0; i < len; i++) {
diff --git a/secp256k1.c b/secp256k1.c
index cbed98888..57a5a8677 100644
--- a/secp256k1.c
+++ b/secp256k1.c
@@ -34,7 +34,7 @@ const bignum256 order256k1 = {
 .val = {0x10364141, 0x3f497a33, 0x348a03bb, 0x2bb739ab, 0x3ffffeba, 0x3fffffff, 0x3fffffff, 0x3fffffff, 0xffff}};
 
 const bignum256 order256k1_half = {
-.val = {0x281b20a0, 0x3fa4bd19, 0x3a4501dd, 0x15db9cd5, 0x3fffff5d, 0x3fffffff, 0x3fffffff, 0x3fffffff, 0x00007fff}};
+.val = {0x281b20a0, 0x3fa4bd19, 0x3a4501dd, 0x15db9cd5, 0x3fffff5d, 0x3fffffff, 0x3fffffff, 0x3fffffff, 0x7fff}};
 
 const bignum256 three_over_two256k1 = {
 .val = {0x3ffffe19, 0x3ffffffd, 0x3fffffff, 0x3fffffff, 0x3fffffff, 0x3fffffff, 0x3fffffff, 0x3fffffff, 0x7fff}};