diff --git a/lisp/ob-clojure.el b/lisp/ob-clojure.el
index 6f1425a84..b424cf48f 100644
--- a/lisp/ob-clojure.el
+++ b/lisp/ob-clojure.el
@@ -101,13 +101,13 @@
 
 (defcustom ob-clojure-babashka-command (executable-find "bb")
   "Path to the babashka executable."
-  :type 'file
+  :type '(choice file (const nil))
   :group 'org-babel
   :package-version '(Org . "9.6"))
 
 (defcustom ob-clojure-nbb-command (executable-find "nbb")
   "Path to the nbb executable."
-  :type 'file
+  :type '(choice file (const nil))
   :group 'org-babel
   :package-version '(Org . "9.6"))
 
diff --git a/lisp/org.el b/lisp/org.el
index be922a5da..ab6212dac 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -1408,7 +1408,7 @@ URI regexps are applied to both URLs and Org files requesting
 remote resources."
   :group 'org
   :package-version '(Org . "9.6")
-  :type '(list regexp))
+  :type '(repeat regexp))
 
 (defcustom org-open-non-existing-files nil
   "Non-nil means `org-open-file' opens non-existing files.
diff --git a/lisp/ox-md.el b/lisp/ox-md.el
index dee6dbf1f..01e0aa049 100644
--- a/lisp/ox-md.el
+++ b/lisp/ox-md.el
@@ -87,7 +87,7 @@ included into another document or application that reserves top-level
 headings for its own use."
   :group 'org-export-md
   :package-version '(Org . "9.6")
-  :type 'string)
+  :type 'natnum)