diff --git a/ox-blackfriday.el b/ox-blackfriday.el
index 67efcc6..b72ae50 100644
--- a/ox-blackfriday.el
+++ b/ox-blackfriday.el
@@ -705,27 +705,20 @@ This function is adapted from `org-html-special-block'."
           ;;   #+end_summary
           ;;   Here are the details.
           ;;   #+end_details
-          (setq contents
-                (let* (;; A closing </p> tag is added at the end.. the
-                       ;; opening <p> tag for that is later added in
-                       ;; the `str2' var.  Insert a newline before
-                       ;; that tag for the reason explained below
-                       ;; using the emacs-lisp Markdown code block.
-                       (str1 (concat contents "\n</p>"))
-                       ;; Detect the summary closing tag "</summary>".
-                       ;; If found, add the opening <p> tag with
-                       ;; "details" class after that, so that CSS
-                       ;; rules can be set specific to the details
-                       ;; portion using "details .details".
-                       (str2 (replace-regexp-in-string
-                              "<summary>\\(?:.\\|\n\\)*</summary>"
-                              "\\&\n<p class=\"details\">"
-                              str1))
-                       (has-summary (not (string= str1 str2))))
-                  ;; (message "[DBG details/summary]: is-open:%S `%s' `%s'" is-open str1 str2)
-                  (unless has-summary
-                    (setq str2 (concat "<p class=\"details\">" str1)))
-                  str2))
+          (let ((p-open "<p class=\"details\">"))
+            (setq contents
+                  (concat
+                   ;; Wrap the "details" portion in the <details> tag
+                   ;; with '<p class="details"> .. </p>'.  With that,
+                   ;; CSS rules can be set specific to that details
+                   ;; portion using "details .details".
+                   (if (string-match "\\(?1:<summary>\\(?:.\\|\n\\)*</summary>\\)" contents) ;If summary exists
+                       (replace-match (format "\\1\n%s" p-open) nil nil contents 1)
+                     (concat p-open contents))
+                   ;; A newline is inserted before the closing </p>
+                   ;; tag for the reason explained below using the
+                   ;; emacs-lisp Markdown code block.
+                   "\n</p>")))
           ;; Insert the "open" attribute only if user has ":open t" in
           ;; "#+attr_html".
           (when (org-string-nw-p attr-str)