diff --git a/sys/net/application_layer/telnet/telnet_server.c b/sys/net/application_layer/telnet/telnet_server.c
index d11f2b47bac5..c167a0a053f4 100644
--- a/sys/net/application_layer/telnet/telnet_server.c
+++ b/sys/net/application_layer/telnet/telnet_server.c
@@ -227,7 +227,7 @@ static void *telnet_thread(void *arg)
                 continue;
             }
 
-            if (res < 0) {
+            if (res <= 0) {
                 break;
             }