diff --git a/src/filesystem-utils.lisp b/src/filesystem-utils.lisp
index d0cc795..6ca159e 100644
--- a/src/filesystem-utils.lisp
+++ b/src/filesystem-utils.lisp
@@ -419,17 +419,17 @@
 (defparameter *temporary-directories-created* ())
 
 (defun temporary-directory (&optional (temp-parent-directory nil))
-  (let ((tmpdir (or temp-parent-directory
-                    (os-utils:default-temp-dir)))
-        (directory-path (if tmpdir
-                            (nix:mkdtemp (format nil "~a~a"
-                                                 tmpdir
-                                                 config:+program-name+))
-                            (nix:mkdtemp (format nil "~atmp~a"
-                                                 *directory-sep*
-                                                 config:+program-name+)))))
-      (push directory-path *temporary-directories-created*)
-      directory-path)))
+  (let* ((tmpdir (or temp-parent-directory
+                     (os-utils:default-temp-dir)))
+         (directory-path (if tmpdir
+                             (nix:mkdtemp (format nil "~a~a"
+                                                  tmpdir
+                                                  config:+program-name+))
+                             (nix:mkdtemp (format nil "~atmp~a"
+                                                  *directory-sep*
+                                                  config:+program-name+)))))
+    (push directory-path *temporary-directories-created*)
+    directory-path))
 
 (cffi:defcfun (ffi-fnmatch "fnmatch")
   :int