diff --git a/index.html b/index.html
index d50dfe4..3020181 100644
--- a/index.html
+++ b/index.html
@@ -184,6 +184,7 @@
             new NumeralSystemInput("Binary", new NumeralSystem(2, "01")),
             new NumeralSystemInput("Octal", new NumeralSystem(8, "01234567")),
             new NumeralSystemInput("Decimal", new NumeralSystem(10, "0123456789")),
+            new NumeralSystemInput("Duodecimal", new NumeralSystem(12, "0123456789ab", caseSensitive = false)),
             new NumeralSystemInput("Hexadecimal", new NumeralSystem(16, "0123456789abcdef", caseSensitive = false)),
             new Base64NumeralSystemInput("Base64"),
             new NumeralSystemInput(