     (cons replacements cursor)))
 
 (defun clang-format--replace (offset length &optional text)
-  (goto-char offset)
-  (delete-char length)
-  (when text
-    (insert text)))
+  (let ((start (byte-to-position (1+ offset)))
+        (end (byte-to-position (+ 1 offset length))))
+    (goto-char start)
+    (delete-region start end)
+    (when text
+      (insert text))))
 
 ;;;###autoload
-(defun clang-format-region (start end &optional style)
+(defun clang-format-region (char-start char-end &optional style)
   "Use clang-format to format the code between START and END according to STYLE.
 If called interactively uses the region or the current statement if there
 is no active region.  If no style is given uses `clang-format-style'."

                      (apply #'clang-format--replace rpl))
                    replacements))
            (when cursor
              (goto-char cursor))))
      (delete-file temp-file)
      (when (buffer-name temp-buffer) (kill-buffer temp-buffer)))))


                 "-output-replacements-xml"
                 "-assume-filename" (or (buffer-file-name) "")
                 "-style" style
                 "-offset" (number-to-string start)
                 "-length" (number-to-string (- end start))
                 "-cursor" (number-to-string cursor)))
          (setq stderr
                (with-temp-buffer
                  (insert-file-contents temp-file)
