diff --git a/common/iobuf.c b/common/iobuf.c
--- a/common/iobuf.c
+++ b/common/iobuf.c
@@ -909,7 +909,7 @@
 		    }
 		  else if (c == 255)
 		    {
-		      a->size = iobuf_get_noeof (chain) << 24;
+		      a->size = (size_t)iobuf_get_noeof (chain) << 24;
 		      a->size |= iobuf_get_noeof (chain) << 16;
 		      a->size |= iobuf_get_noeof (chain) << 8;
 		      if ((c = iobuf_get (chain)) == -1)