diff --git a/mm/iob/iob_clone.c b/mm/iob/iob_clone.c
index 9f34221e6ff..109e3d6bd80 100644
--- a/mm/iob/iob_clone.c
+++ b/mm/iob/iob_clone.c
@@ -140,7 +140,7 @@ int iob_clone_partial(FAR struct iob_s *iob1, unsigned int len,
   while (iob2 != NULL)
     {
       avail2 = CONFIG_IOB_BUFSIZE - iob2->io_offset;
-      if (offset2 < avail2)
+      if ((int)(offset2 - avail2) < 0)
         {
           break;
         }