diff --git a/include/libssh/ed25519.h b/include/libssh/ed25519.h
index 7b48856c..8a3263c8 100644
--- a/include/libssh/ed25519.h
+++ b/include/libssh/ed25519.h
@@ -56,8 +56,8 @@ int crypto_sign_ed25519_keypair(ed25519_pubkey pk, ed25519_privkey sk);
  * @return    0 on success.
  */
 int crypto_sign_ed25519(
-    unsigned char *sm,unsigned long long *smlen,
-    const unsigned char *m,unsigned long long mlen,
+    unsigned char *sm, uint64_t *smlen,
+    const unsigned char *m, uint64_t mlen,
     const ed25519_privkey sk);
 
 /** @internal
@@ -71,8 +71,8 @@ int crypto_sign_ed25519(
  * @returns   0 on success (supposedly).
  */
 int crypto_sign_ed25519_open(
-    unsigned char *m,unsigned long long *mlen,
-    const unsigned char *sm,unsigned long long smlen,
+    unsigned char *m, uint64_t *mlen,
+    const unsigned char *sm, uint64_t smlen,
     const ed25519_pubkey pk);
 
 /** @} */
diff --git a/src/external/ed25519.c b/src/external/ed25519.c
index b0d9b15b..8cd58591 100644
--- a/src/external/ed25519.c
+++ b/src/external/ed25519.c
@@ -63,9 +63,9 @@ static void get_hram(unsigned char *hram,
                      const unsigned char *sm,
                      const unsigned char *pk,
                      unsigned char *playground,
-                     unsigned long long smlen)
+                     uint64_t smlen)
 {
-    unsigned long long i;
+    uint64_t i;
     SHA512CTX ctx;
     for (i =  0;i < 32;++i)    playground[i] = sm[i];
     for (i = 32;i < 64;++i)    playground[i] = pk[i-32];
@@ -111,9 +111,9 @@ int crypto_sign_ed25519_keypair(unsigned char *pk,
 }
 
 int crypto_sign_ed25519(unsigned char *sm,
-                        unsigned long long *smlen,
+                        uint64_t *smlen,
                         const unsigned char *m,
-                        unsigned long long mlen,
+                        uint64_t mlen,
                         const unsigned char *sk)
 {
     sc25519 sck, scs, scsk;
@@ -122,7 +122,7 @@ int crypto_sign_ed25519(unsigned char *sm,
     unsigned char r[32];
     unsigned char s[32];
     unsigned char extsk[64];
-    unsigned long long i;
+    uint64_t i;
     unsigned char hmg[SHA512_DIGEST_LEN];
     unsigned char hram[SHA512_DIGEST_LEN];
 
@@ -174,9 +174,9 @@ int crypto_sign_ed25519(unsigned char *sm,
 }
 
 int crypto_sign_ed25519_open(unsigned char *m,
-                             unsigned long long *mlen,
+                             uint64_t *mlen,
                              const unsigned char *sm,
-                             unsigned long long smlen,
+                             uint64_t smlen,
                              const unsigned char *pk)
 {
     unsigned int i;
@@ -186,7 +186,7 @@ int crypto_sign_ed25519_open(unsigned char *m,
     sc25519 schram, scs;
     unsigned char hram[SHA512_DIGEST_LEN];
 
-    *mlen = (unsigned long long) -1;
+    *mlen = (uint64_t) -1;
     if (smlen < 64) return -1;
 
     if (ge25519_unpackneg_vartime(&get1, pk)) {
diff --git a/src/pki_ed25519.c b/src/pki_ed25519.c
index 981a74b6..0eaa4943 100644
--- a/src/pki_ed25519.c
+++ b/src/pki_ed25519.c
@@ -85,7 +85,7 @@ int pki_ed25519_sign(const ssh_key privkey,
 {
     int rc;
     uint8_t *buffer;
-    unsigned long long dlen = 0;
+    uint64_t dlen = 0;
 
     buffer = malloc(hlen + ED25519_SIG_LEN);
     if (buffer == NULL) {
@@ -125,7 +125,7 @@ int pki_ed25519_verify(const ssh_key pubkey,
                        const unsigned char *hash,
                        size_t hlen)
 {
-    unsigned long long mlen = 0;
+    uint64_t mlen = 0;
     uint8_t *buffer;
     uint8_t *buffer2;
     int rc;