diff --git a/module/system/repl/command.scm b/module/system/repl/command.scm
index ca7450610..8b0422dbd 100644
--- a/module/system/repl/command.scm
+++ b/module/system/repl/command.scm
@@ -235,6 +235,8 @@
      (define-meta-command ((name category) repl () . datums)
        docstring b0 b1 ...))
 
+    ;; These cases (with category #f) will only produce functional
+    ;; commands if the name is already in the *command-table*.
     ((_ (name repl (expression0 ...) . datums) docstring b0 b1 ...)
      (define-meta-command ((name #f) repl (expression0 ...) . datums)
        docstring b0 b1 ...))