diff -up ./gnutls.el.old ./gnutls.el
--- ./gnutls.el.old	2022-02-14 12:59:06.442427021 +0000
+++ ./gnutls.el	2022-02-14 13:34:59.580342409 +0000
@@ -222,6 +222,27 @@ trust and key files, and priority string
 (declare-function gnutls-boot "gnutls.c" (proc type proplist))
 (declare-function gnutls-errorp "gnutls.c" (error))
 (defvar gnutls-log-level)               ; gnutls.c
+(defcustom gnutls-verify-flags 256
+  "Set the default verify flags used - default is 256.
+VERIFY-FLAGS is a numeric OR of verification flags only for
+`gnutls-x509pki' connections.  See GnuTLS' x509.h for details;
+here's a recent version of the list.
+
+    GNUTLS_VERIFY_DISABLE_CA_SIGN = 1,
+    GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT = 2,
+    GNUTLS_VERIFY_DO_NOT_ALLOW_SAME = 4,
+    GNUTLS_VERIFY_ALLOW_ANY_X509_V1_CA_CRT = 8,
+    GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD2 = 16,
+    GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5 = 32,
+    GNUTLS_VERIFY_DISABLE_TIME_CHECKS = 64,
+    GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS = 128,
+    GNUTLS_VERIFY_DO_NOT_ALLOW_X509_V1_CA_CRT = 256
+
+It must be omitted, a number, or nil; if omitted or nil it
+defaults to GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT (256)."
+  :group 'gnutls
+  :type '(choice (const nil) number)
+)
 
 (cl-defun gnutls-negotiate
     (&rest spec
@@ -247,7 +268,7 @@ For the meaning of the rest of the param
                   :crlfiles crlfiles
                   :keylist keylist
                   :min-prime-bits min-prime-bits
-                  :verify-flags verify-flags
+                  :verify-flags (or verify-flags gnutls-verify-flags)
                   :verify-error verify-error
                   :verify-hostname-error verify-hostname-error))
          ret)
@@ -356,7 +377,7 @@ defaults to GNUTLS_VERIFY_ALLOW_X509_V1_
                 :trustfiles ,trustfiles
                 :crlfiles ,crlfiles
                 :keylist ,keylist
-                :verify-flags ,verify-flags
+                :verify-flags ,(or verify-flags gnutls-verify-flags)
                 :verify-error ,verify-error
                 :callbacks nil)))