diff --git a/apps/dnet-orgs-database-application/src/main/java/eu/dnetlib/organizations/controller/PublicApiController.java b/apps/dnet-orgs-database-application/src/main/java/eu/dnetlib/organizations/controller/PublicApiController.java
index 31877154..3adc8244 100644
--- a/apps/dnet-orgs-database-application/src/main/java/eu/dnetlib/organizations/controller/PublicApiController.java
+++ b/apps/dnet-orgs-database-application/src/main/java/eu/dnetlib/organizations/controller/PublicApiController.java
@@ -37,7 +37,7 @@ public class PublicApiController {
 			res.sendError(HttpStatus.BAD_REQUEST.value(), "Invalid year");
 		}
 
-		final String filename = String.format("%s_%s_%s.log", year, month, country);
+		final String filename = String.format("%04d_%02d_%s.log", year, month, country);
 
 		res.setContentType(MediaType.TEXT_PLAIN.getType());
 		res.setHeader("Content-Disposition", "attachment; filename=" + filename);