diff --git a/configure.ac b/configure.ac
index 76fd4ab..290b92a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -59,7 +59,7 @@ if test -n "$kbuilddir"; then
 		echo "$kmajor.$kminor.$kmicro.$kstable in $kbuilddir";
 		if test "$kmajor" -gt 4 -o "$kmajor" -eq 4 -a "$kminor" -gt 15; then
 			echo "WARNING: That kernel version is not officially supported yet. Continue at own luck.";
-		elif test "$kmajor" -eq 4 -a "$kminor" -ge 14; then
+		elif test "$kmajor" -eq 4 -a "$kminor" -ge 15; then
 			:
 		else
 			echo "WARNING: That kernel version is not officially supported.";
diff --git a/doc/changelog.txt b/doc/changelog.txt
index a5bbcbe..18c9bf7 100644
--- a/doc/changelog.txt
+++ b/doc/changelog.txt
@@ -4,7 +4,7 @@ HEAD
 Enhancements:
 - support for Linux up to 4.15
 Changes:
-- remove support for Linux 3.7--4.13
+- remove support for Linux 3.7--4.14
 
 
 v2.14 (2017-11-22)
diff --git a/extensions/compat_xtables.h b/extensions/compat_xtables.h
index faf5dd8..d08354a 100644
--- a/extensions/compat_xtables.h
+++ b/extensions/compat_xtables.h
@@ -8,8 +8,8 @@
 
 #define DEBUGP Use__pr_debug__instead
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 14, 0)
-#	warning Kernels below 4.14 not supported.
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 15, 0)
+#	warning Kernels below 4.15 not supported.
 #endif
 
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
diff --git a/extensions/pknock/xt_pknock.c b/extensions/pknock/xt_pknock.c
index 7be0345..c76901a 100644
--- a/extensions/pknock/xt_pknock.c
+++ b/extensions/pknock/xt_pknock.c
@@ -357,18 +357,10 @@ has_logged_during_this_minute(const struct peer *peer)
  *
  * @r: rule
  */
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 15, 0)
 static void peer_gc(struct timer_list *tl)
-#else
-static void peer_gc(unsigned long r)
-#endif
 {
 	unsigned int i;
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 15, 0)
 	struct xt_pknock_rule *rule = from_timer(rule, tl, timer);
-#else
-	struct xt_pknock_rule *rule = (struct xt_pknock_rule *)r;
-#endif
 	struct peer *peer;
 	struct list_head *pos, *n;
 
@@ -475,15 +467,7 @@ add_rule(struct xt_pknock_mtinfo *info)
 	rule->peer_head      = alloc_hashtable(peer_hashsize);
 	if (rule->peer_head == NULL)
 		goto out;
-
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 15, 0)
 	timer_setup(&rule->timer, peer_gc, 0);
-#else
-	init_timer(&rule->timer);
-	rule->timer.function	= peer_gc;
-	rule->timer.data	= (unsigned long)rule;
-#endif
-
 	rule->status_proc = proc_create_data(info->rule_name, 0, pde,
 	                    &pknock_proc_ops, rule);
 	if (rule->status_proc == NULL)