1 files changed, 1 insertions, 1 deletions

diff --git a/lisp/progmodes/sql.el b/lisp/progmodes/sql.el
index c4baef82e27..4029b2e8d3b 100644
--- a/lisp/progmodes/sql.el
+++ b/lisp/progmodes/sql.el
@@ -285,7 +285,7 @@ file.  Since that is a plaintext file, this could be dangerous."
 (defcustom sql-default-directory nil
   "Default directory for SQL processes."
   :version "24.5"
-  :type 'string
+  :type '(choice (const nil) string)
   :group 'SQL
   :safe 'stringp)