diff --git a/src/openvpn/ssl_verify.c b/src/openvpn/ssl_verify.c
index 76cb9f19..4206cf9c 100644
--- a/src/openvpn/ssl_verify.c
+++ b/src/openvpn/ssl_verify.c
@@ -166,7 +166,7 @@ tls_lock_username(struct tls_multi *multi, const char *username)
     }
     else
     {
-        if (username)
+        if (username && *username)
         {
             multi->locked_username = string_alloc(username, NULL);
         }