diff --git a/src/openvpn/auth_token.c b/src/openvpn/auth_token.c
index ceae68f6..10c9dde6 100644
--- a/src/openvpn/auth_token.c
+++ b/src/openvpn/auth_token.c
@@ -38,7 +38,7 @@ auth_token_kt(void)
     kt.cipher = "none";
     kt.digest = "SHA256";
 
-    if (!kt.digest)
+    if (!md_valid(kt.digest))
     {
         msg(M_WARN, "ERROR: --tls-crypt requires HMAC-SHA-256 support.");
         return (struct key_type) { 0 };
diff --git a/src/openvpn/crypto_backend.h b/src/openvpn/crypto_backend.h
index abf1b876..78260057 100644
--- a/src/openvpn/crypto_backend.h
+++ b/src/openvpn/crypto_backend.h
@@ -520,8 +520,7 @@ static inline bool md_defined(const char* mdname)
  *
  * @param digest        Name of the digest to verify, e.g. \c MD5).
  *
- * @return              A statically allocated structure containing parameters
- *                      for the given message digest.
+ * @return              the availability of the digest of the given name.
  */
 bool md_valid(const char *digest);
 
diff --git a/src/openvpn/tls_crypt.c b/src/openvpn/tls_crypt.c
index 610168b0..aae2a917 100644
--- a/src/openvpn/tls_crypt.c
+++ b/src/openvpn/tls_crypt.c
@@ -59,7 +59,7 @@ tls_crypt_kt(void)
         msg(M_WARN, "ERROR: --tls-crypt requires AES-256-CTR support.");
         return (struct key_type) { 0 };
     }
-    if (cipher_valid(kt.digest))
+    if (!md_valid(kt.digest))
     {
         msg(M_WARN, "ERROR: --tls-crypt requires HMAC-SHA-256 support.");
         return (struct key_type) { 0 };