diff --git a/daemon/dir.c b/daemon/dir.c
index ad1c7c987..1ca62868e 100644
--- a/daemon/dir.c
+++ b/daemon/dir.c
@@ -185,31 +185,22 @@ do_is_dir (const char *path)
 }
 
 char *
-do_mkdtemp (char *template)
+do_mkdtemp (const char *template)
 {
-  char *r;
-
-  NEED_ROOT (return NULL);
-  ABS_PATH (template, return NULL);
+  char *writable = strdup (template);
+  if (writable == NULL) {
+    reply_with_perror ("strdup");
+    return NULL;
+  }
 
   CHROOT_IN;
-  r = mkdtemp (template);
+  char *r = mkdtemp (writable);
   CHROOT_OUT;
 
   if (r == NULL) {
     reply_with_perror ("mkdtemp: %s", template);
-    return NULL;
+    free (writable);
   }
 
-  /* The caller will free template AND try to free the return value,
-   * so we must make a copy here.
-   */
-  if (r == template) {
-    r = strdup (template);
-    if (r == NULL) {
-      reply_with_perror ("strdup");
-      return NULL;
-    }
-  }
   return r;
 }
diff --git a/src/generator.ml b/src/generator.ml
index 49fd3ce87..60e3a0281 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -2621,8 +2621,7 @@ containing C<dir>.
 It is an interface to the L<scrub(1)> program.  See that
 manual page for more details.");
 
-(* FIXME: make this a WritableString? *)
-  ("mkdtemp", (RString "dir", [String "template"]), 117, [],
+  ("mkdtemp", (RString "dir", [Pathname "template"]), 117, [],
    [InitBasicFS, Always, TestRun (
       [["mkdir"; "/tmp"];
        ["mkdtemp"; "/tmp/tmpXXXXXX"]])],
@@ -4762,7 +4761,7 @@ and generate_daemon_actions () =
              | Pathname n ->
                  pr "  char *%s = args.%s;\n" n n;
                  pr "  ABS_PATH (%s, goto done);\n" n;
-	     | Device n ->
+             | Device n ->
                  pr "  char *%s = args.%s;\n" n n;
                  pr "  RESOLVE_DEVICE (%s, goto done);" n;
              | String n -> pr "  char *%s = args.%s;\n" n n
@@ -6843,7 +6842,6 @@ DESTROY (g)
       iteri (
         fun i ->
           function
-	  (* FIXME: ? *)
           | Pathname n | Device n | String n | FileIn n | FileOut n ->
               pr "      char *%s;\n" n
           | OptString n ->