diff --git a/lisp/ox-html.el b/lisp/ox-html.el
index 4b2f3c513..76ccbbc4a 100644
--- a/lisp/ox-html.el
+++ b/lisp/ox-html.el
@@ -1638,7 +1638,8 @@ a communication channel."
      (org-html--make-attribute-string
       (org-combine-plists
        (list :src source
-	     :alt (if (string-match-p "^ltxpng/" source)
+	     :alt (if (string-match-p
+		       (concat "^" org-preview-latex-image-directory) source)
 		      (org-html-encode-plain-text
 		       (org-find-text-property-in-string 'org-latex-src source))
 		    (file-name-nondirectory source)))
diff --git a/lisp/ox-odt.el b/lisp/ox-odt.el
index d353a3a2e..104319a9d 100644
--- a/lisp/ox-odt.el
+++ b/lisp/ox-odt.el
@@ -3730,7 +3730,8 @@ contextual information."
 		 (cache-dir (file-name-directory input-file))
 		 (cache-subdir (concat
 				(cl-case processing-type
-				  ((dvipng imagemagick) "ltxpng/")
+				  ((dvipng imagemagick)
+				   org-preview-latex-image-directory)
 				  (mathml "ltxmathml/"))
 				(file-name-sans-extension
 				 (file-name-nondirectory input-file))))