diff --git a/master/slave_config.c b/master/slave_config.c
index 11cb48bbe713eb9d1ee1c8a515b40ed815b28147..7c33dbf2b60581b3950af549f71ff75a595ee424 100644
--- a/master/slave_config.c
+++ b/master/slave_config.c
@@ -512,7 +512,7 @@ int ecrt_slave_config_pdos(ec_slave_config_t *sc,
     for (i = 0; i < n_syncs; i++) {
         sync_info = &syncs[i];
 
-        if (sync_info->index == 0xff)
+        if (sync_info->index == (uint8_t) EC_END)
             break;
 
         if (sync_info->index >= EC_MAX_SYNC_MANAGERS) {