diff --git a/modules/access/v4l2/demux.c b/modules/access/v4l2/demux.c
index 23e6e114fa28d28f4b441990f17032e2f51d33b1..987ad0000cda61335120d44ee29330a7d9b5437b 100644
--- a/modules/access/v4l2/demux.c
+++ b/modules/access/v4l2/demux.c
@@ -472,7 +472,7 @@ static int InitVideo (demux_t *demux, int fd)
         sys->blocksize = fmt.fmt.pix.sizeimage;
         sys->bufv = NULL;
         entry = ReadThread;
-        msg_Dbg (demux, "reading %zu bytes at a time", sys->blocksize);
+        msg_Dbg (demux, "reading %"PRIu32" bytes at a time", sys->blocksize);
     }
     else
     {