diff --git a/src/rest.c b/src/rest.c
index a86a9ec..1894111 100644
--- a/src/rest.c
+++ b/src/rest.c
@@ -1904,7 +1904,7 @@ static int og_dbi_update_client_repo(struct og_dbi *dbi, const char *mac,
 
 	result = dbi_conn_queryf(dbi->conn,
 				 "UPDATE ordenadores SET idrepositorio=%u "
-				 "WHERE mac='%u'",
+				 "WHERE mac='%s'",
 				 repo_id, mac);
 
 	if (!result) {