diff --git a/sys/arm64/arm64/gicv3_its.c b/sys/arm64/arm64/gicv3_its.c
--- a/sys/arm64/arm64/gicv3_its.c
+++ b/sys/arm64/arm64/gicv3_its.c
@@ -2204,10 +2204,8 @@
 	DEVMETHOD_END
 };
 
-#define its_baseclasses its_fdt_baseclasses
 DEFINE_CLASS_1(its, gicv3_its_fdt_driver, gicv3_its_fdt_methods,
     sizeof(struct gicv3_its_softc), gicv3_its_driver);
-#undef its_baseclasses
 
 EARLY_DRIVER_MODULE(its_fdt, gic, gicv3_its_fdt_driver, 0, 0,
     BUS_PASS_INTERRUPT + BUS_PASS_ORDER_MIDDLE);
@@ -2276,10 +2274,8 @@
 	DEVMETHOD_END
 };
 
-#define its_baseclasses its_acpi_baseclasses
 DEFINE_CLASS_1(its, gicv3_its_acpi_driver, gicv3_its_acpi_methods,
     sizeof(struct gicv3_its_softc), gicv3_its_driver);
-#undef its_baseclasses
 
 EARLY_DRIVER_MODULE(its_acpi, gic, gicv3_its_acpi_driver, 0, 0,
     BUS_PASS_INTERRUPT + BUS_PASS_ORDER_MIDDLE);
diff --git a/sys/arm64/arm64/nexus.c b/sys/arm64/arm64/nexus.c
--- a/sys/arm64/arm64/nexus.c
+++ b/sys/arm64/arm64/nexus.c
@@ -444,9 +444,7 @@
 	DEVMETHOD_END,
 };
 
-#define nexus_baseclasses nexus_fdt_baseclasses
 DEFINE_CLASS_1(nexus, nexus_fdt_driver, nexus_fdt_methods, 1, nexus_driver);
-#undef nexus_baseclasses
 
 EARLY_DRIVER_MODULE(nexus_fdt, root, nexus_fdt_driver, 0, 0,
     BUS_PASS_BUS + BUS_PASS_ORDER_FIRST);
@@ -534,10 +532,8 @@
 	DEVMETHOD_END,
 };
 
-#define nexus_baseclasses nexus_acpi_baseclasses
 DEFINE_CLASS_1(nexus, nexus_acpi_driver, nexus_acpi_methods, 1,
     nexus_driver);
-#undef nexus_baseclasses
 
 EARLY_DRIVER_MODULE(nexus_acpi, root, nexus_acpi_driver, 0, 0,
     BUS_PASS_BUS + BUS_PASS_ORDER_FIRST);
diff --git a/sys/sys/kobj.h b/sys/sys/kobj.h
--- a/sys/sys/kobj.h
+++ b/sys/sys/kobj.h
@@ -107,72 +107,76 @@
  */
 #define DECLARE_CLASS(name) extern struct kobj_class name
 
-/*
- * Define a class with no base classes (api backward-compatible. with
- * FreeBSD-5.1 and earlier).
- */
+/* [DEPRECATED] */
 #define DEFINE_CLASS(name, methods, size)     		\
 DEFINE_CLASS_0(name, name ## _class, methods, size)
 
-/*
- * Define a class with no base classes. Use like this:
- *
- * DEFINE_CLASS_0(foo, foo_class, foo_methods, sizeof(foo_softc));
- */
+/* [DEPRECATED] */
 #define DEFINE_CLASS_0(name, classvar, methods, size)	\
 							\
 struct kobj_class classvar = {				\
 	#name, methods, size, NULL			\
 }
 
-/*
- * Define a class inheriting a single base class. Use like this:
- *
- * DEFINE_CLASS_1(foo, foo_class, foo_methods, sizeof(foo_softc),
- *			  bar);
- */
+/* [DEPRECATED] */
 #define DEFINE_CLASS_1(name, classvar, methods, size,	\
 		       base1)				\
-							\
-static kobj_class_t name ## _baseclasses[] =		\
-	{ &base1, NULL };				\
-struct kobj_class classvar = {				\
-	#name, methods, size, name ## _baseclasses	\
-}
+	PUBLIC_DEFINE_CLASSN(name, classvar, methods, size, base1)
+
+/* [DEPRECATED] */
+#define DEFINE_CLASS_2(name, classvar, methods, size,	\
+	               base1, base2)			\
+	PUBLIC_DEFINE_CLASSN(name, classvar, methods, size, base1, base2)
 
 /*
- * Define a class inheriting two base classes. Use like this:
+ * Define a public class inheriting any number (including zero) base
+ * classes. Use like this:
  *
- * DEFINE_CLASS_2(foo, foo_class, foo_methods, sizeof(foo_softc),
- *			  bar, baz);
+ * PUBLIC_DEFINE_CLASSN(foo, foo_class, foo_methods, sizeof(foo_softc)[,
+ *                        bar[, baz[, foobar]]]);
  */
-#define DEFINE_CLASS_2(name, classvar, methods, size,	\
-	               base1, base2)			\
-							\
-static kobj_class_t name ## _baseclasses[] =		\
-	{ &base1,					\
-	  &base2, NULL };				\
-struct kobj_class classvar = {				\
-	#name, methods, size, name ## _baseclasses	\
+#define PUBLIC_DEFINE_CLASSN(_name, classvar, _methods, _size, ...)	\
+									\
+__VA_OPT__(static kobj_class_t classvar ## _baseclasses[] = {		\
+	__DEFINE_CLASSN_BASE_EXPANDER0(__VA_ARGS__)NULL });		\
+struct kobj_class classvar = {						\
+	.name = #_name,							\
+	.methods = _methods,						\
+	.size = _size,							\
+	__VA_OPT__(.baseclasses = classvar ## _baseclasses,)		\
 }
 
 /*
- * Define a class inheriting three base classes. Use like this:
+ * Define a private class inheriting any number (including zero) base
+ * classes. Use like this:
  *
- * DEFINE_CLASS_3(foo, foo_class, foo_methods, sizeof(foo_softc),
- *			  bar, baz, foobar);
+ * PRIVATE_DEFINE_CLASSN(foo, foo_class, foo_methods, sizeof(foo_softc)[,
+ *                        bar[, baz[, foobar]]]);
  */
-#define DEFINE_CLASS_3(name, classvar, methods, size,	\
-		       base1, base2, base3)		\
-							\
-static kobj_class_t name ## _baseclasses[] =		\
-	{ &base1,					\
-	  &base2,					\
-	  &base3, NULL };				\
-struct kobj_class classvar = {				\
-	#name, methods, size, name ## _baseclasses	\
+#define PRIVATE_DEFINE_CLASSN(_name, classvar, _methods, _size, ...)	\
+									\
+__VA_OPT__(static kobj_class_t classvar ## _baseclasses[] = {		\
+	__DEFINE_CLASSN_BASE_EXPANDER0(__VA_ARGS__)NULL });		\
+static struct kobj_class classvar = {					\
+	.name = #_name,							\
+	.methods = _methods,						\
+	.size = _size,							\
+	__VA_OPT__(.baseclasses = classvar ## _baseclasses,)		\
 }
 
+/* Helper macros for the above, adding ampersands to parent class names */
+#define __DEFINE_CLASSN_BASE_EXPANDER0(base, ...)			\
+	&base, __VA_OPT__(__DEFINE_CLASSN_BASE_EXPANDER1(__VA_ARGS__))
+
+#define __DEFINE_CLASSN_BASE_EXPANDER1(base, ...)			\
+	&base, __VA_OPT__(__DEFINE_CLASSN_BASE_EXPANDER2(__VA_ARGS__))
+
+#define __DEFINE_CLASSN_BASE_EXPANDER2(base, ...)			\
+	&base, __VA_OPT__(__DEFINE_CLASSN_BASE_EXPANDER3(__VA_ARGS__))
+
+#define __DEFINE_CLASSN_BASE_EXPANDER3(base, ...)			\
+	_Static_assert(false, "Expansion exceeded limit of DEFINE_CLASSN()")
+
 /*
  * Compile the method table in a class.
  */