diff --git a/README.md b/README.md
index fd776dd..aa03eb7 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,8 @@
 A toy C library that converts numbers to and from [BCD](https://en.wikipedia.org/wiki/Binary-coded_decimal).
 I suggest you don't use it.
 
+Named after [half a byte](https://en.wikipedia.org/wiki/Nibble).
+
 ## Installation
 
 Don't. The makefile only includes a test target, because I want to test my code.