diff --git a/Tests/Certificate.hs b/Tests/Certificate.hs
--- a/Tests/Certificate.hs
+++ b/Tests/Certificate.hs
@@ -191,7 +191,7 @@
 
 -- | Used to build a certificate extension.
 mkExtension :: Extension a => Bool -> a -> ExtensionRaw
-mkExtension crit ext = ExtensionRaw (extOID ext) crit (extEncode ext)
+mkExtension crit ext = ExtensionRaw (extOID ext) crit (extEncodeBs ext)
 
 -- | Default extensions in leaf certificates.
 leafStdExts :: [ExtensionRaw]
diff --git a/x509-validation.cabal b/x509-validation.cabal
--- a/x509-validation.cabal
+++ b/x509-validation.cabal
@@ -1,5 +1,5 @@
 Name:                x509-validation
-version:             1.6.7
+version:             1.6.8
 Description:         X.509 Certificate and CRL validation
 License:             BSD3
 License-file:        LICENSE
@@ -50,7 +50,7 @@
                    , hourglass
                    , asn1-types
                    , asn1-encoding
-                   , x509
+                   , x509 >= 1.7.1
                    , x509-store
                    , x509-validation
                    , cryptonite