diff --git a/src/bigarray/dune b/src/bigarray/dune
index 563e400..76d1426 100644
--- a/src/bigarray/dune
+++ b/src/bigarray/dune
@@ -6,7 +6,7 @@
   (modules IterBigarray IterBigarrayShims_)
   (wrapped false)
   (optional)
-  (flags :standard -w +a-4-42-44-48-50-58-32-60@8 -safe-string)
+  (flags :standard -warn-error -a+8 -safe-string)
   (ocamlopt_flags :standard (:include ../flambda.flags)))
 
 (executable
diff --git a/src/dune b/src/dune
index b8396d2..5cd78b4 100644
--- a/src/dune
+++ b/src/dune
@@ -19,7 +19,7 @@
   (public_name iter)
   (wrapped false)
   (modules Iter IterLabels Iter_shims_)
-  (flags :standard -w +a-4-42-44-48-50-58-32-60@8 -safe-string -nolabels)
+  (flags :standard -warn-error -a+8 -safe-string -nolabels)
   (ocamlopt_flags :standard (:include flambda.flags))
   (libraries bytes result))
 
diff --git a/src/sequence/dune b/src/sequence/dune
index 288f8c9..70ce027 100644
--- a/src/sequence/dune
+++ b/src/sequence/dune
@@ -3,4 +3,5 @@
   (name sequence)
   (public_name sequence)
   (wrapped false)
+  (flags :standard -warn-error -a+8 -safe-string)
   (libraries iter))