diff --git a/src/crypto.h b/src/crypto.h
index 2dbae162..94a5b356 100644
--- a/src/crypto.h
+++ b/src/crypto.h
@@ -191,7 +191,7 @@ _libssh2_ed25519_new_private(libssh2_ed25519_ctx **ed_ctx,
 int
 _libssh2_ed25519_new_public(libssh2_ed25519_ctx **ed_ctx,
                             LIBSSH2_SESSION *session,
-                            const char *raw_pub_key, const uint8_t key_len);
+                            const unsigned char *raw_pub_key, const uint8_t key_len);
 
 int
 _libssh2_ed25519_sign(libssh2_ed25519_ctx *ctx, LIBSSH2_SESSION *session,
diff --git a/src/hostkey.c b/src/hostkey.c
index f76eea25..78471c3f 100644
--- a/src/hostkey.c
+++ b/src/hostkey.c
@@ -795,7 +795,7 @@ hostkey_method_ssh_ed25519_init(LIBSSH2_SESSION * session,
                                 size_t hostkey_data_len,
                                 void **abstract)
 {
-    const char *s;
+    const unsigned char *s;
     unsigned long len, key_len;
     libssh2_ed25519_ctx *ctx = NULL;
 
diff --git a/src/openssl.c b/src/openssl.c
index 99e46121..31f1814a 100644
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -1778,7 +1778,7 @@ _libssh2_ed25519_new_private_frommemory(libssh2_ed25519_ctx ** ed_ctx,
 int
 _libssh2_ed25519_new_public(libssh2_ed25519_ctx ** ed_ctx,
                             LIBSSH2_SESSION * session,
-                            const char *raw_pub_key, const uint8_t key_len)
+                            const unsigned char *raw_pub_key, const uint8_t key_len)
 {
     libssh2_ed25519_ctx *ctx = NULL;
     EVP_PKEY *public_key = NULL;