diff --git a/src/Tiny_httpd_dir.ml b/src/Tiny_httpd_dir.ml
index 34a5ca03..117aa1e3 100644
--- a/src/Tiny_httpd_dir.ml
+++ b/src/Tiny_httpd_dir.ml
@@ -1,7 +1,6 @@
 module S = Tiny_httpd_server
 module U = Tiny_httpd_util
 module Html = Tiny_httpd_html
-module Pf = Printf
 
 type dir_behavior =
   | Index | Lists | Index_or_lists | Forbidden
diff --git a/src/dune b/src/dune
index 27ee21cd..41e5bcb5 100644
--- a/src/dune
+++ b/src/dune
@@ -3,7 +3,7 @@
   (name tiny_httpd)
   (public_name tiny_httpd)
   (libraries threads seq)
-  (flags :standard -safe-string -warn-error -a+8)
+  (flags :standard -safe-string -strict-sequence -w +a-4-40-42 -warn-error -a+8)
   (wrapped false))
 
 (rule