diff --git a/lib/pop3.c b/lib/pop3.c
index a7657171c5..ba13e7d6bd 100644
--- a/lib/pop3.c
+++ b/lib/pop3.c
@@ -517,7 +517,7 @@ static CURLcode pop3_statemach_act(struct connectdata *conn)
       if(data->set.ftp_ssl && !conn->ssl[FIRSTSOCKET].use) {
         /* We don't have a SSL/TLS connection yet, but SSL is requested. Switch
            to TLS connection now */
-        result = Curl_pp_sendf(&pop3c->pp, "STARTTLS", NULL);
+        result = Curl_pp_sendf(&pop3c->pp, "STLS");
         state(conn, POP3_STARTTLS);
       }
       else