diff --git a/src/wcmUSB.c b/src/wcmUSB.c
index b7b3d060..33f8b67a 100644
--- a/src/wcmUSB.c
+++ b/src/wcmUSB.c
@@ -1369,7 +1369,7 @@ mod_buttons(WacomCommonPtr common, unsigned int buttons, unsigned int btn, Bool
 		return buttons;
 	}
 
-	mask = 1 << btn;
+	mask = 1u << btn;
 
 	if (state)
 		buttons |= mask;