diff --git a/book/src/registers.md b/book/src/registers.md
index 2edf7e27a..d8e40ff22 100644
--- a/book/src/registers.md
+++ b/book/src/registers.md
@@ -44,6 +44,7 @@ Some registers have special behavior when read from and written to.
 | `#`                | Selection indices (first selection is `1`, second is `2`, etc.) | This register is not writable |
 | `.`                | Contents of the current selections | This register is not writable |
 | `%`                | Name of the current file | This register is not writable |
+| `/`                | Folder which contains the current file | This register is not writable |
 | `+`                | Reads from the system clipboard | Joins and yanks to the system clipboard |
 | `*`                | Reads from the primary clipboard | Joins and yanks to the primary clipboard |