diff --git a/src/rfc2131.c b/src/rfc2131.c
index e27cd29..fc54aab 100644
--- a/src/rfc2131.c
+++ b/src/rfc2131.c
@@ -413,7 +413,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
 		for (o2 = offset + 5; o2 < offset + len + 5; o2 += elen + 1)
 		  { 
 		    elen = option_uint(opt, o2, 1);
-		    if ((o2 + elen + 1 <= option_len(opt)) &&
+		    if ((o2 + elen + 1 <= (unsigned)option_len(opt)) &&
 			(match = match_bytes(o, option_ptr(opt, o2 + 1), elen)))
 		      break;
 		  }