diff --git a/src/libsodium/crypto_sign/ed25519/ref10/sign.c b/src/libsodium/crypto_sign/ed25519/ref10/sign.c
index 7aeb07f2..2e4a730c 100644
--- a/src/libsodium/crypto_sign/ed25519/ref10/sign.c
+++ b/src/libsodium/crypto_sign/ed25519/ref10/sign.c
@@ -37,8 +37,7 @@ _crypto_sign_ed25519_clamp(unsigned char k[32])
 static void
 _crypto_sign_ed25519_synthetic_r_hv(crypto_hash_sha512_state *hs,
                                     unsigned char nonce[64],
-                                    unsigned char sk_copy[64],
-                                    const unsigned char sk[64])
+                                    const unsigned char sk[32])
 {
     static const unsigned char B[32] = {
         0x58, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
@@ -49,14 +48,12 @@ _crypto_sign_ed25519_synthetic_r_hv(crypto_hash_sha512_state *hs,
     static const unsigned char zeros[16] = { 0x00 };
     static const unsigned char empty_labelset[3] = { 0x02, 0x00, 0x00 };
 
-    memcpy(sk_copy, sk, 32);
-    _crypto_sign_ed25519_clamp(sk_copy);
     crypto_hash_sha512_update(hs, B, 32);
     crypto_hash_sha512_update(hs, empty_labelset, 3);
     randombytes_buf(nonce, 32);
     crypto_hash_sha512_update(hs, nonce, 32);
     crypto_hash_sha512_update(hs, zeros, 16 - (32 + 3 + 32) % 16);
-    crypto_hash_sha512_update(hs, sk_copy, 32);
+    crypto_hash_sha512_update(hs, sk, 32);
     /* empty pad2 */
     crypto_hash_sha512_update(hs, empty_labelset, 3);
     crypto_hash_sha512_update(hs, sk + 32, 32);
@@ -75,18 +72,21 @@ _crypto_sign_ed25519_detached(unsigned char *sig, unsigned long long *siglen_p,
     unsigned char            hram[64];
     ge_p3                    R;
 
-#ifdef ED25519_NONDETERMINISTIC
     _crypto_sign_ed25519_ref10_hinit(&hs, prehashed);
-    _crypto_sign_ed25519_synthetic_r_hv(&hs, nonce, az, sk);
+
+#ifdef ED25519_NONDETERMINISTIC
+    memcpy(az, sk, 32);
+    _crypto_sign_ed25519_synthetic_r_hv(&hs, nonce, sk);
 #else
     crypto_hash_sha512(az, sk, 32);
-    _crypto_sign_ed25519_clamp(az);
-    _crypto_sign_ed25519_ref10_hinit(&hs, prehashed);
     crypto_hash_sha512_update(&hs, az + 32, 32);
 #endif
+
     crypto_hash_sha512_update(&hs, m, mlen);
     crypto_hash_sha512_final(&hs, nonce);
 
+    _crypto_sign_ed25519_clamp(az);
+
     memmove(sig + 32, sk + 32, 32);
 
     sc_reduce(nonce);