diff --git a/sys/compat/linuxkpi/common/include/acpi/video.h b/sys/compat/linuxkpi/common/include/acpi/video.h
--- a/sys/compat/linuxkpi/common/include/acpi/video.h
+++ b/sys/compat/linuxkpi/common/include/acpi/video.h
@@ -29,6 +29,7 @@
 #ifndef _LINUXKPI_ACPI_VIDEO_H_
 #define _LINUXKPI_ACPI_VIDEO_H_
 
+#include <sys/types.h>
 #include <sys/errno.h>
 
 #define	ACPI_VIDEO_CLASS	"video"
@@ -47,4 +48,15 @@
 {
 }
 
+static inline void
+acpi_video_register_backlight(void)
+{
+}
+
+static inline bool
+acpi_video_backlight_use_native(void)
+{
+	return (true);
+}
+
 #endif	/* _LINUXKPI_ACPI_VIDEO_H_ */