diff --git a/sys/kern/kern_environment.c b/sys/kern/kern_environment.c
index 511ab697a525..c05c063efd57 100644
--- a/sys/kern/kern_environment.c
+++ b/sys/kern/kern_environment.c
@@ -544,6 +544,36 @@ getenv_uint(const char *name, unsigned int *data)
 	return (rval);
 }
 
+/*
+ * Return an int64_t value from an environment variable.
+ */
+int
+getenv_int64(const char *name, int64_t *data)
+{
+	quad_t tmp;
+	int64_t rval;
+
+	rval = getenv_quad(name, &tmp);
+	if (rval)
+		*data = (int64_t) tmp;
+	return (rval);
+}
+
+/*
+ * Return an uint64_t value from an environment variable.
+ */
+int
+getenv_uint64(const char *name, uint64_t *data)
+{
+	quad_t tmp;
+	uint64_t rval;
+
+	rval = getenv_quad(name, &tmp);
+	if (rval)
+		*data = (uint64_t) tmp;
+	return (rval);
+}
+
 /*
  * Return a long value from an environment variable.
  */
@@ -649,6 +679,22 @@ tunable_ulong_init(void *data)
 	TUNABLE_ULONG_FETCH(d->path, d->var);
 }
 
+void
+tunable_int64_init(void *data)
+{
+	struct tunable_int64 *d = (struct tunable_int64 *)data;
+
+	TUNABLE_INT64_FETCH(d->path, d->var);
+}
+
+void
+tunable_uint64_init(void *data)
+{
+	struct tunable_uint64 *d = (struct tunable_uint64 *)data;
+
+	TUNABLE_UINT64_FETCH(d->path, d->var);
+}
+
 void
 tunable_quad_init(void *data)
 {
diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
index dddf087ff15b..02628babb2c7 100644
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -316,6 +316,44 @@ struct tunable_ulong {
 
 #define	TUNABLE_ULONG_FETCH(path, var)	getenv_ulong((path), (var))
 
+/*
+ * int64_t
+ */
+extern void tunable_int64_init(void *);
+struct tunable_int64 {
+	const char *path;
+	int64_t *var;
+};
+#define	TUNABLE_INT64(path, var)				\
+	static struct tunable_int64 __CONCAT(__tunable_int64_, __LINE__) = { \
+		(path),						\
+		(var),						\
+	};							\
+	SYSINIT(__CONCAT(__Tunable_init_, __LINE__),		\
+	    SI_SUB_TUNABLES, SI_ORDER_MIDDLE, tunable_int64_init, \
+	    &__CONCAT(__tunable_int64_, __LINE__))
+
+#define	TUNABLE_INT64_FETCH(path, var)	getenv_int64((path), (var))
+
+/*
+ * uint64_t
+ */
+extern void tunable_uint64_init(void *);
+struct tunable_uint64 {
+	const char *path;
+	uint64_t *var;
+};
+#define	TUNABLE_UINT64(path, var)				\
+	static struct tunable_ulong __CONCAT(__tunable_uint64_, __LINE__) = { \
+		(path),						\
+		(var),						\
+	};							\
+	SYSINIT(__CONCAT(__Tunable_init_, __LINE__),		\
+	    SI_SUB_TUNABLES, SI_ORDER_MIDDLE, tunable_uint64_init, \
+	    &__CONCAT(__tunable_uint64_, __LINE__))
+
+#define	TUNABLE_UINT64_FETCH(path, var)	getenv_uint64((path), (var))
+
 /*
  * quad
  */
diff --git a/sys/sys/systm.h b/sys/sys/systm.h
index 9c6e45082170..34ad5ba58dd8 100644
--- a/sys/sys/systm.h
+++ b/sys/sys/systm.h
@@ -322,6 +322,8 @@ int	getenv_uint(const char *name, unsigned int *data);
 int	getenv_long(const char *name, long *data);
 int	getenv_ulong(const char *name, unsigned long *data);
 int	getenv_string(const char *name, char *data, int size);
+int	getenv_int64(const char *name, int64_t *data);
+int	getenv_uint64(const char *name, uint64_t *data);
 int	getenv_quad(const char *name, quad_t *data);
 int	kern_setenv(const char *name, const char *value);
 int	kern_unsetenv(const char *name);