diff --git a/pycoax/examples/20_char_map.py b/pycoax/examples/20_char_map.py
index dcf6609..1e47cd1 100755
--- a/pycoax/examples/20_char_map.py
+++ b/pycoax/examples/20_char_map.py
@@ -61,4 +61,4 @@ with open_example_serial_interface() as interface:
 
     interface.execute([LoadAddressCounterHi(0), LoadAddressCounterLo(79)])
 
-    interface.execute(WriteData(bytes[0xff]))
+    interface.execute(WriteData(bytes([0xff])))