diff --git a/include/linux/input.h b/include/linux/input.h
index 6b28048..32cb825 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -445,6 +445,7 @@
 #define BTN_STYLUS2		0x14c
 #define BTN_TOOL_DOUBLETAP	0x14d
 #define BTN_TOOL_TRIPLETAP	0x14e
+#define BTN_TOOL_QUADTAP	0x14f	/* Four fingers on trackpad */
 
 #define BTN_WHEEL		0x150
 #define BTN_GEAR_DOWN		0x150