diff --git a/alphabet/alphabet.go b/alphabet/alphabet.go
index 36d615fb..7355a83f 100644
--- a/alphabet/alphabet.go
+++ b/alphabet/alphabet.go
@@ -1,3 +1,6 @@
+/*
+Package alphabet provides structs for defining biological sequence alphabets.
+*/
 package alphabet
 
 import "fmt"