diff --git a/conf.c b/conf.c
index 3a360ef..a604357 100644
--- a/conf.c
+++ b/conf.c
@@ -235,6 +235,9 @@ static int nts_refresh = 2419200; /* 4 weeks */
 static int nts_rotate = 604800; /* 1 week */
 static char *nts_trusted_cert_file = NULL;
 
+/* Number of clock updates needed to enable certificate time checks */
+static int no_cert_time_check = 0;
+
 /* Flag disabling use of system trusted certificates */
 static int no_system_cert = 0;
 
@@ -545,6 +548,8 @@ CNF_ParseLine(const char *filename, int number, char *line)
     parse_int(p, &min_samples);
   } else if (!strcasecmp(command, "minsources")) {
     parse_int(p, &min_sources);
+  } else if (!strcasecmp(command, "nocerttimecheck")) {
+    parse_int(p, &no_cert_time_check);
   } else if (!strcasecmp(command, "noclientlog")) {
     no_client_log = parse_null(p);
   } else if (!strcasecmp(command, "nosystemcert")) {
@@ -2158,3 +2163,11 @@ CNF_GetNoSystemCert(void)
 {
   return no_system_cert;
 }
+
+/* ================================================== */
+
+int
+CNF_GetNoCertTimeCheck(void)
+{
+  return no_cert_time_check;
+}
diff --git a/conf.h b/conf.h
index 7c92470..4d27ef1 100644
--- a/conf.h
+++ b/conf.h
@@ -150,5 +150,6 @@ extern int CNF_GetNtsRefresh(void);
 extern int CNF_GetNtsRotate(void);
 extern char *CNF_GetNtsTrustedCertFile(void);
 extern int CNF_GetNoSystemCert(void);
+extern int CNF_GetNoCertTimeCheck(void);
 
 #endif /* GOT_CONF_H */
diff --git a/nts_ke_session.c b/nts_ke_session.c
index 78c9735..a27216f 100644
--- a/nts_ke_session.c
+++ b/nts_ke_session.c
@@ -40,6 +40,7 @@
 #include "util.h"
 
 #include <gnutls/gnutls.h>
+#include <gnutls/x509.h>
 
 #define INVALID_SOCK_FD (-8)
 
@@ -89,6 +90,8 @@ static gnutls_priority_t priority_cache;
 
 static int credentials_counter = 0;
 
+static int clock_updates = 0;
+
 /* ================================================== */
 
 static void
@@ -209,6 +212,7 @@ create_tls_session(int server_mode, int sock_fd, const char *server_name,
   unsigned char alpn_name[sizeof (NKE_ALPN_NAME)];
   gnutls_session_t session;
   gnutls_datum_t alpn;
+  unsigned int flags;
   int r;
 
   r = gnutls_init(&session, GNUTLS_NONBLOCK | (server_mode ? GNUTLS_SERVER : GNUTLS_CLIENT));
@@ -221,7 +225,15 @@ create_tls_session(int server_mode, int sock_fd, const char *server_name,
     r = gnutls_server_name_set(session, GNUTLS_NAME_DNS, server_name, strlen(server_name));
     if (r < 0)
       goto error;
-    gnutls_session_set_verify_cert(session, server_name, 0);
+
+    flags = 0;
+
+    if (clock_updates < CNF_GetNoCertTimeCheck()) {
+      flags |= GNUTLS_VERIFY_DISABLE_TIME_CHECKS | GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS;
+      DEBUG_LOG("Disabled time checks");
+    }
+
+    gnutls_session_set_verify_cert(session, server_name, flags);
   }
 
   r = gnutls_priority_set(session, priority);
@@ -552,6 +564,16 @@ get_time(time_t *t)
 
 /* ================================================== */
 
+static void
+handle_step(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  if (change_type != LCL_ChangeUnknownStep && clock_updates < INT_MAX)
+    clock_updates++;
+}
+
+/* ================================================== */
+
 static int gnutls_initialised = 0;
 
 static void
@@ -576,6 +598,8 @@ init_gnutls(void)
   gnutls_global_set_time_function(get_time);
 
   gnutls_initialised = 1;
+
+  LCL_AddParameterChangeHandler(handle_step, NULL);
 }
 
 /* ================================================== */
@@ -585,6 +609,8 @@ deinit_gnutls(void)
 {
   assert(gnutls_initialised);
 
+  LCL_RemoveParameterChangeHandler(handle_step, NULL);
+
   gnutls_priority_deinit(priority_cache);
   gnutls_global_deinit();
   gnutls_initialised = 0;
diff --git a/test/unit/nts_ke_client.c b/test/unit/nts_ke_client.c
index 74a17e4..80d5232 100644
--- a/test/unit/nts_ke_client.c
+++ b/test/unit/nts_ke_client.c
@@ -24,6 +24,7 @@
 #ifdef FEAT_NTS
 
 #include <nts_ke_client.c>
+#include <local.h>
 
 static void
 prepare_response(NKSN_Instance session, int valid)
@@ -110,6 +111,7 @@ test_unit(void)
   for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
     CNF_ParseLine(NULL, i + 1, conf[i]);
 
+  LCL_Initialise();
   NKC_Initialise();
 
   SCK_GetLoopbackIPAddress(AF_INET, &addr.ip_addr);
@@ -128,6 +130,7 @@ test_unit(void)
   NKC_DestroyInstance(inst);
 
   NKC_Finalise();
+  LCL_Finalise();
   CNF_Finalise();
 }
 #else