diff --git a/src/boot/boot.janet b/src/boot/boot.janet
index 4a38030b..f87672c7 100644
--- a/src/boot/boot.janet
+++ b/src/boot/boot.janet
@@ -592,6 +592,9 @@
   * `:when condition` -- only evaluates the current loop body when `condition`
     is true.
 
+  * `:unless condition` -- only evaluates the current loop body when `condition`
+    is false.
+
   The `loop` macro always evaluates to nil.
   ```
   [head & body]