diff --git a/src/libsodium/crypto_sign/ed25519/ref10/keypair.c b/src/libsodium/crypto_sign/ed25519/ref10/keypair.c
index 8a7b444c..b7a0f71f 100644
--- a/src/libsodium/crypto_sign/ed25519/ref10/keypair.c
+++ b/src/libsodium/crypto_sign/ed25519/ref10/keypair.c
@@ -71,7 +71,7 @@ crypto_sign_ed25519_sk_to_curve25519(unsigned char *curve25519_sk,
 
     crypto_hash_sha512(h, ed25519_sk,
                        crypto_sign_ed25519_SECRETKEYBYTES -
-                           crypto_sign_ed25519_PUBLICKEYBYTES);
+                       crypto_sign_ed25519_PUBLICKEYBYTES);
     h[0] &= 248;
     h[31] &= 127;
     h[31] |= 64;