diff --git a/lib/cert_service.ml b/lib/cert_service.ml
index fa230b0..11acecf 100644
--- a/lib/cert_service.ml
+++ b/lib/cert_service.ml
@@ -14,12 +14,11 @@ type t = {
 }
 
 let check_csr_dn csr dn =
-  if X509.Distinguished_name.equal
-      dn
-      (X509.Signing_request.info csr).subject
+  let subject = (X509.Signing_request.info csr).subject in
+  if X509.Distinguished_name.equal dn subject
   then Ok ()
   else R.error_msgf "Bad subject in csr: %a"
-      X509.Distinguished_name.pp (X509.Signing_request.info csr).subject
+      X509.Distinguished_name.pp subject
 
 let sign t csr user =
   let subject =