diff --git a/compat.h b/compat.h
index 8461c3d..c4f29e9 100644
--- a/compat.h
+++ b/compat.h
@@ -216,7 +216,7 @@ struct timeval {
 	long tv_usec; /* microseconds */
 };
 
-unsigned long timeval_to_jiffies(const struct timeval *tv)
+static inline unsigned long timeval_to_jiffies(const struct timeval *tv)
 {
 	return timespec64_to_jiffies(&(struct timespec64){
 				     tv->tv_sec,
@@ -225,6 +225,20 @@ unsigned long timeval_to_jiffies(const struct timeval *tv)
 }
 #endif
 
+#ifndef HAVE_STRLCPY
+static inline size_t strlcpy(char *dest, const char *src, size_t size)
+{
+	size_t ret = strlen(src);
+
+	if (size) {
+		size_t len = (ret >= size) ? size - 1 : ret;
+		__builtin_memcpy(dest, src, len);
+		dest[len] = '\0';
+	}
+	return ret;
+}
+#endif
+
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,35)
 # ifdef ktime_to_timeval
 /* ktime_to_timeval is defined on 64bit and inline on 32bit cpu */
@@ -380,10 +394,10 @@ static int sockaddr_cmp(const struct sockaddr_storage *sa1, const struct sockadd
 	return 0;
 }
 
-#ifndef IN6PTON_XDIGIT
+#ifndef HAVE_IN6_PTON
 #define hex_to_bin compat_hex_to_bin
 /* lib/hexdump.c */
-int hex_to_bin(char ch)
+static inline int hex_to_bin(char ch)
 {
 	if ((ch >= '0') && (ch <= '9'))
 		return ch - '0';
@@ -593,7 +607,7 @@ int in6_pton(const char *src, int srclen,
 		*end = s;
 	return ret;
 }
-#endif /* IN6PTON_XDIGIT */
+#endif /* HAVE_IN6_PTON */
 
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4,2,0)
 # define sock_create_kern(f, t, p, s) sock_create_kern(&init_net, f, t, p, s)
@@ -712,40 +726,6 @@ static inline void do_gettimeofday(struct timeval *tv)
 }
 #endif
 
-#define TOLOWER(x) ((x) | 0x20)
-unsigned long long strtoul(const char *cp, char **endp, unsigned int base)
-{
-	unsigned long long result = 0;
-
-	if (!base) {
-		if (cp[0] == '0') {
-			if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
-				base = 16;
-			else
-				base = 8;
-		} else {
-			base = 10;
-		}
-	}
-
-	if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
-		cp += 2;
-
-	while (isxdigit(*cp)) {
-		unsigned int value;
-
-		value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
-		if (value >= base)
-			break;
-		result = result * base + value;
-		cp++;
-	}
-	if (endp)
-		*endp = (char *)cp;
-
-	return result;
-}
-
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(5,12,0)
 /*
  * find_module() is unexported in v5.12:
diff --git a/gen_compat_def b/gen_compat_def
index a9cb95e..f9796f7 100755
--- a/gen_compat_def
+++ b/gen_compat_def
@@ -129,6 +129,10 @@ kbuild_test_ref    totalram_pages linux/mm.h
 kbuild_test_member nf_ct_event_notifier.ct_event net/netfilter/nf_conntrack_ecache.h
 # 6.4: 0199849acd07 ("sysctl: remove register_sysctl_paths()")
 kbuild_test_symbol register_sysctl_paths linux/sysctl.h
+# 6.8: d26270061ae6 ("string: Remove strlcpy()")
+kbuild_test_symbol strlcpy linux/string.h
+# 2.6.18 lacks in6_pton and in4_pton
+kbuild_test_symbol in6_pton linux/inet.h
 
 echo "// End of compat_def.h"
 
diff --git a/ipt_NETFLOW.c b/ipt_NETFLOW.c
index eee8074..3b717a3 100644
--- a/ipt_NETFLOW.c
+++ b/ipt_NETFLOW.c
@@ -29,6 +29,9 @@
 #include <linux/in6.h>
 #include <linux/inet.h>
 #include <linux/kernel.h>
+#if LINUX_VERSION_CODE > KERNEL_VERSION(5,10,0)
+#include <linux/kstrtox.h>
+#endif
 #include <linux/ip.h>
 #include <linux/udp.h>
 #include <linux/icmp.h>
@@ -2396,7 +2399,7 @@ static int add_destinations(const char *ptr)
 				++end;
 			if (succ &&
 			    (*end == ':' || *end == '.' || *end == 'p' || *end == '#'))
-				sin6->sin6_port = htons(strtoul(++end, (char **)&end, 0));
+				sin6->sin6_port = htons(simple_strtoul(++end, (char **)&end, 0));
 			if (succ && *end == '@') {
 				++end;
 				sout->sin6_family = AF_INET6;
@@ -2411,7 +2414,7 @@ static int add_destinations(const char *ptr)
 			sin->sin_port = htons(2055);
 			succ = in4_pton(ptr, len, (u8 *)&sin->sin_addr, -1, &end);
 			if (succ && *end == ':')
-				sin->sin_port = htons(strtoul(++end, (char **)&end, 0));
+				sin->sin_port = htons(simple_strtoul(++end, (char **)&end, 0));
 			if (succ && *end == '@') {
 				++end;
 				sout->sin_family = AF_INET;