diff --git a/system/ymodem/rb_main.c b/system/ymodem/rb_main.c
index 41878eae1..1beb8c2a2 100644
--- a/system/ymodem/rb_main.c
+++ b/system/ymodem/rb_main.c
@@ -171,7 +171,7 @@ static int handler(FAR struct ymodem_ctx_s *ctx)
 
   if (ctx->packet_type == YMODEM_FILENAME_PACKET)
     {
-      char temp[PATH_MAX];
+      char temp[PATH_MAX + 1];
       FAR char *filename;
 
       if (priv->fd > 0)
@@ -216,7 +216,7 @@ static int handler(FAR struct ymodem_ctx_s *ctx)
 
       if (priv->foldname != NULL)
         {
-          snprintf(temp, PATH_MAX, "%s/%s", priv->foldname,
+          snprintf(temp, sizeof(temp), "%s/%s", priv->foldname,
                    filename);
           filename = temp;
         }
diff --git a/system/ymodem/ymodem.c b/system/ymodem/ymodem.c
index ca7e30ec9..1f8cf6ff6 100644
--- a/system/ymodem/ymodem.c
+++ b/system/ymodem/ymodem.c
@@ -231,7 +231,7 @@ recv_packet:
   if ((total_seq & 0xff) - 1 == ctx->header[1])
     {
       ymodem_debug("recv_file: Received the previous packet that has"
-                   "been received, continue %lu %u\n", total_seq,
+                   "been received, continue %" PRIu32 " %u\n", total_seq,
                    ctx->header[1]);
 
       ctx->header[0] = ACK;
@@ -239,7 +239,7 @@ recv_packet:
     }
   else if ((total_seq & 0xff) != ctx->header[1])
     {
-      ymodem_debug("recv_file: total seq error:%lu %u\n", total_seq,
+      ymodem_debug("recv_file: total seq error:%" PRIu32 " %u\n", total_seq,
                    ctx->header[1]);
       ctx->header[0] = CRC;
       goto recv_packet;