diff --git a/server/modules/routing/binlog/blr.c b/server/modules/routing/binlog/blr.c
index e5bfbd23e..93a5aa32a 100644
--- a/server/modules/routing/binlog/blr.c
+++ b/server/modules/routing/binlog/blr.c
@@ -247,7 +247,7 @@ char	*defuuid;
 	{
 		my_uuid(defuuid);
 		if ((inst->uuid = (char *)malloc(38)) != NULL)
-			sprintf(inst->uuid, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+			sprintf(inst->uuid, "%02hhx%02hhx%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx",
 			defuuid[0], defuuid[1], defuuid[2], defuuid[3],
 			defuuid[4], defuuid[5], defuuid[6], defuuid[7],
 			defuuid[8], defuuid[9], defuuid[10], defuuid[11],