diff --git a/lib/zip_set_archive_comment.c b/lib/zip_set_archive_comment.c
index bbb9a73..f71bea7 100644
--- a/lib/zip_set_archive_comment.c
+++ b/lib/zip_set_archive_comment.c
@@ -42,7 +42,12 @@
 ZIP_EXTERN int
 zip_set_archive_comment(struct zip *za, const char *comment, int len)
 {
-    char *tmpcom;
+    struct zip_string *cstr;
+
+    if (ZIP_IS_RDONLY(za)) {
+	_zip_error_set(&za->error, ZIP_ER_RDONLY, 0);
+	return -1;
+    }
 
     if (len < 0 || len > MAXCOMLEN
 	|| (len > 0 && comment == NULL)) {
@@ -50,26 +55,31 @@
 	return -1;
     }
 
-    if (ZIP_IS_RDONLY(za)) {
-	_zip_error_set(&za->error, ZIP_ER_RDONLY, 0);
-	return -1;
-    }
-
-    if (_zip_guess_encoding(comment, len) == ZIP_ENCODING_CP437) {
-	_zip_error_set(&za->error, ZIP_ER_INVAL, 0);
-	return -1;
-    }
-
     if (len > 0) {
-	if ((tmpcom=(char *)_zip_memdup(comment, len, &za->error)) == NULL)
+	if ((cstr=_zip_string_new((const zip_uint8_t *)comment, len, &za->error)) == NULL)
 	    return -1;
+
+	if (_zip_guess_encoding(cstr, ZIP_ENCODING_UNKNOWN) == ZIP_ENCODING_CP437) {
+	    _zip_string_free(cstr);
+	    _zip_error_set(&za->error, ZIP_ER_INVAL, 0);
+	    return -1;
+	}
     }
     else
-	tmpcom = NULL;
+	cstr = NULL;
 
-    free(za->ch_comment);
-    za->ch_comment = tmpcom;
-    za->ch_comment_len = len;
+    _zip_string_free(za->comment_changes);
+    za->comment_changes = NULL;
+
+    if (((za->comment_orig && _zip_string_equal(za->comment_orig, cstr))
+	 || (za->comment_orig == NULL && cstr == NULL))) {
+	_zip_string_free(cstr);
+	za->comment_changed = 0;
+    }
+    else {
+	za->comment_changes = cstr;
+	za->comment_changed = 1;
+    }
     
     return 0;
 }