define-markup-commands.scm: Fix bad parameter type for \on-the-fly

diff --git a/scm/define-markup-commands.scm b/scm/define-markup-commands.scm
index 803b691215cf864950838d7280fecb1731968c7b..aa022974e38adaa9637d5d1c512d12bb3e54b6f7 100644 (file)
--- a/scm/define-markup-commands.scm
+++ b/scm/define-markup-commands.scm
@@ -1918,7 +1918,7 @@ returns an empty markup.
         empty-stencil)))
 
 (define-markup-command (on-the-fly layout props procedure arg)
-  (symbol? markup?)
+  (procedure? markup?)
   #:category other
   "Apply the @var{procedure} markup command to @var{arg}.
 @var{procedure} should take a single argument."