diff --git a/config/spl-build.m4 b/config/spl-build.m4
index 08609b80a..fbe880836 100644
--- a/config/spl-build.m4
+++ b/config/spl-build.m4
@@ -30,7 +30,6 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
 	SPL_AC_CTL_NAME
 	SPL_AC_VMALLOC_INFO
 	SPL_AC_PDE_DATA
-	SPL_AC_FLS64
 	SPL_AC_SET_NORMALIZED_TIMESPEC_EXPORT
 	SPL_AC_SET_NORMALIZED_TIMESPEC_INLINE
 	SPL_AC_TIMESPEC_SUB
@@ -993,24 +992,6 @@ AC_DEFUN([SPL_AC_CTL_NAME], [
 	])
 ])
 
-dnl #
-dnl # 2.6.16 API change.
-dnl # Check if 'fls64()' is available
-dnl #
-AC_DEFUN([SPL_AC_FLS64],
-	[AC_MSG_CHECKING([whether fls64() is available])
-	SPL_LINUX_TRY_COMPILE([
-		#include <linux/bitops.h>
-	],[
-		return fls64(0);
-	],[
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_FLS64, 1, [fls64() is available])
-	],[
-		AC_MSG_RESULT(no)
-	])
-])
-
 dnl #
 dnl # 2.6.26 API change, set_normalized_timespec() is exported.
 dnl #
diff --git a/include/linux/bitops_compat.h b/include/linux/bitops_compat.h
index 9c55844ad..0a3ac16f4 100644
--- a/include/linux/bitops_compat.h
+++ b/include/linux/bitops_compat.h
@@ -27,17 +27,5 @@
 
 #include <linux/bitops.h>
 
-#ifndef HAVE_FLS64
-
-static inline int fls64(__u64 x)
-{
-       __u32 h = x >> 32;
-       if (h)
-               return fls(h) + 32;
-       return fls(x);
-}
-
-#endif /* HAVE_FLS64 */
-
 #endif /* _SPL_BITOPS_COMPAT_H */
 
diff --git a/include/sys/sysmacros.h b/include/sys/sysmacros.h
index 33e92b6d8..c56d7e12a 100644
--- a/include/sys/sysmacros.h
+++ b/include/sys/sysmacros.h
@@ -152,13 +152,12 @@ extern char spl_version[32];
 extern unsigned long spl_hostid;
 
 /* Missing misc functions */
-extern int highbit(unsigned long i);
-extern int highbit64(uint64_t i);
 extern uint32_t zone_get_hostid(void *zone);
 extern void spl_setup(void);
 extern void spl_cleanup(void);
 
-#define makedevice(maj,min) makedev(maj,min)
+#define	highbit64(x)		fls64(x)
+#define	makedevice(maj,min)	makedev(maj,min)
 
 /* common macros */
 #ifndef MIN
diff --git a/module/spl/spl-generic.c b/module/spl/spl-generic.c
index 3e8f874de..1059fb3cc 100644
--- a/module/spl/spl-generic.c
+++ b/module/spl/spl-generic.c
@@ -64,68 +64,6 @@ DECLARE_WAIT_QUEUE_HEAD(spl_kallsyms_lookup_name_waitq);
 kallsyms_lookup_name_t spl_kallsyms_lookup_name_fn = SYMBOL_POISON;
 #endif
 
-int
-highbit(unsigned long i)
-{
-        register int h = 1;
-        SENTRY;
-
-        if (i == 0)
-                SRETURN(0);
-#if BITS_PER_LONG == 64
-        if (i & 0xffffffff00000000ul) {
-                h += 32; i >>= 32;
-        }
-#endif
-        if (i & 0xffff0000) {
-                h += 16; i >>= 16;
-        }
-        if (i & 0xff00) {
-                h += 8; i >>= 8;
-        }
-        if (i & 0xf0) {
-                h += 4; i >>= 4;
-        }
-        if (i & 0xc) {
-                h += 2; i >>= 2;
-        }
-        if (i & 0x2) {
-                h += 1;
-        }
-        SRETURN(h);
-}
-EXPORT_SYMBOL(highbit);
-
-int
-highbit64(uint64_t i)
-{
-        register int h = 1;
-        SENTRY;
-
-        if (i == 0)
-                SRETURN(0);
-        if (i & 0xffffffff00000000ull) {
-                h += 32; i >>= 32;
-        }
-        if (i & 0xffff0000) {
-                h += 16; i >>= 16;
-        }
-        if (i & 0xff00) {
-                h += 8; i >>= 8;
-        }
-        if (i & 0xf0) {
-                h += 4; i >>= 4;
-        }
-        if (i & 0xc) {
-                h += 2; i >>= 2;
-        }
-        if (i & 0x2) {
-                h += 1;
-        }
-        SRETURN(h);
-}
-EXPORT_SYMBOL(highbit64);
-
 #if BITS_PER_LONG == 32
 /*
  * Support 64/64 => 64 division on a 32-bit platform.  While the kernel
diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c
index 55b265696..8b52dfede 100644
--- a/module/spl/spl-kmem.c
+++ b/module/spl/spl-kmem.c
@@ -977,7 +977,7 @@ spl_sko_from_obj(spl_kmem_cache_t *skc, void *obj)
 static inline uint32_t
 spl_offslab_size(spl_kmem_cache_t *skc)
 {
-	return 1UL << (highbit(spl_obj_size(skc)) + 1);
+	return 1UL << (fls64(spl_obj_size(skc)) + 1);
 }
 
 /*