diff --git a/dkim-bin.opam b/dkim-bin.opam
index dba1f82..2dcf431 100644
--- a/dkim-bin.opam
+++ b/dkim-bin.opam
@@ -27,4 +27,5 @@ depends: [
   "fmt"               {>= "0.8.7"}
   "fpath"
   "dns-client"
+  "alcotest"          {with-test}
 ]
diff --git a/dkim.opam b/dkim.opam
index 682593f..37d1423 100644
--- a/dkim.opam
+++ b/dkim.opam
@@ -35,7 +35,7 @@ depends: [
   "base64"            {>= "3.0.0"}
   "mirage-crypto"     {>= "0.9.2"}
   "mirage-crypto-pk"  {>= "0.9.2"}
-  "x509"              {>= "0.6.3"}
+  "x509"              {>= "0.12.0"}
   "mirage-crypto-rng" {with-test & >= "0.11.0"}
   "alcotest"          {with-test}
 ]