diff --git a/examples/vp8cx_set_ref.c b/examples/vp8cx_set_ref.c
index 5a675788a56ffd8e8b8c04ce42e9a82b1d53f8bf..f87dd35c3a56ac45e99431b39115c20dc2503006 100644
--- a/examples/vp8cx_set_ref.c
+++ b/examples/vp8cx_set_ref.c
@@ -139,7 +139,7 @@ static void write_ivf_frame_header(FILE *outfile,
         return;
 
     pts = pkt->data.frame.pts;
-    mem_put_le32(header, pkt->data.frame.sz);
+    mem_put_le32(header, (unsigned int)pkt->data.frame.sz);
     mem_put_le32(header+4, pts&0xFFFFFFFF);
     mem_put_le32(header+8, pts >> 32);