diff --git a/lisp/htmlfontify.el b/lisp/htmlfontify.el
index 115f67c9560..f8d1e205369 100644
--- a/lisp/htmlfontify.el
+++ b/lisp/htmlfontify.el
@@ -1882,7 +1882,7 @@ Hardly bombproof, but good enough in the context in which it is being used."
 
 (defun hfy-text-p (srcdir file)
   "Is SRCDIR/FILE text?  Use `hfy-istext-command' to determine this."
-  (let* ((cmd (format hfy-istext-command (expand-file-name file srcdir)))
+  (let* ((cmd (format hfy-istext-command (shell-quote-argument (expand-file-name file srcdir))))
          (rsp (shell-command-to-string    cmd)))
     (string-match "text" rsp)))