diff --git a/rmacs/buffer.rkt b/rmacs/buffer.rkt
index 6938bbe..33ea204 100644
--- a/rmacs/buffer.rkt
+++ b/rmacs/buffer.rkt
@@ -50,6 +50,7 @@
          command-window
          command-editor
          (rename-out [make-command command])
+         replace-selector
          invoke
 
          define-key
@@ -347,6 +348,9 @@
                   [(command? buffer-or-command) (command-buffer buffer-or-command)]))
   (command selector buffer window (or editor (buffer-editor buffer)) keyseq prefix-arg))
 
+(define (replace-selector cmd selector)
+  (struct-copy command cmd [selector selector]))
+
 (define (invoke cmd)
   (match-define (command selector buf _ _ keyseq _) cmd)
   (define handler (modeset-lookup-command (buffer-modeset buf) selector))
diff --git a/rmacs/mode/fundamental.rkt b/rmacs/mode/fundamental.rkt
index 21ae5e0..f87cbe6 100644
--- a/rmacs/mode/fundamental.rkt
+++ b/rmacs/mode/fundamental.rkt
@@ -14,8 +14,8 @@
      (buffer-insert! buf (window-point win) (string->rope (string ch)))]
     [_ #f]))
 
-(define-command fundamental-mode (unbound-key-sequence buf #:keyseq keyseq)
-  (invoke (command 'self-insert-command buf #:keyseq keyseq)))
+(define-command fundamental-mode (unbound-key-sequence buf #:command cmd #:keyseq keyseq)
+  (invoke (replace-selector cmd 'self-insert-command)))
 
 (define-key fundamental-mode (list "C-q" '#:default) self-insert-command)