diff --git a/docs/tutorial/building.rst b/docs/tutorial/building.rst
index 1b6bd4c..c0458a9 100644
--- a/docs/tutorial/building.rst
+++ b/docs/tutorial/building.rst
@@ -430,7 +430,7 @@ We will define offset and frequency like we did with amplitude, and we will also
         def waveform(self):
             return int(self.query('?WVF'))
 
-        @waveform
+        @waveform.setter
         def waveform(self, value):
             self.query('!WVF {}'.format(value))