diff --git a/tools/libinput-measure-trackpoint-range b/tools/libinput-measure-trackpoint-range
index eac84e30..4053f9ff 100755
--- a/tools/libinput-measure-trackpoint-range
+++ b/tools/libinput-measure-trackpoint-range
@@ -48,7 +48,7 @@ class Delta(object):
         self.x = x
         self.y = y
 
-    def __bool_(self):
+    def __bool__(self):
         return self.x != 0 or self.y != 0