diff --git a/library/log/elog_file.c b/library/log/elog_file.c
index 591ddf5..9e380eb 100644
--- a/library/log/elog_file.c
+++ b/library/log/elog_file.c
@@ -85,7 +85,7 @@ static bool elog_file_rotate(void)
     fp = NULL;
 
     for (n = local_cfg.max_rotate - 1; n >= 0; --n) {
-        RD_SNPRINTF(oldpath + base, SUFFIX_LEN, n ? ".%d" : "", n - 1);
+        RD_SNPRINTF(oldpath + base, SUFFIX_LEN, n ? ".%04d" : "", n - 1);
         if (n > 9999) n = 9999;
         RD_SNPRINTF(newpath + base, SUFFIX_LEN, ".%04d", n);
         /* remove the old file */