diff --git a/examples/demo/advanced/spec_waterfall.py b/examples/demo/advanced/spec_waterfall.py
index f161ad7b0..5dd6d7d57 100644
--- a/examples/demo/advanced/spec_waterfall.py
+++ b/examples/demo/advanced/spec_waterfall.py
@@ -100,7 +100,7 @@ def map_screen(self, data_array, data_offset=None):
 
 def _create_plot_component(obj):
     # Setup the spectrum plot
-    frequencies = linspace(0.0, float(SAMPLING_RATE) / 2, num=NUM_SAMPLES / 2)
+    frequencies = linspace(0.0, float(SAMPLING_RATE) / 2, num=NUM_SAMPLES // 2)
     obj.spectrum_data = ArrayPlotData(frequency=frequencies)
     empty_amplitude = zeros(NUM_SAMPLES // 2)
     obj.spectrum_data.set_data("amplitude", empty_amplitude)