diff --git a/dtool/src/dtoolutil/filename.h b/dtool/src/dtoolutil/filename.h
index e053b38818..760ccf5ff7 100644
--- a/dtool/src/dtoolutil/filename.h
+++ b/dtool/src/dtoolutil/filename.h
@@ -213,8 +213,8 @@ PUBLISHED:
   bool chdir() const;
   bool touch() const;
   bool unlink() const;
-  bool rename_to(const Filename &other) const;
-  bool copy_to(const Filename &other) const;
+  BLOCKING bool rename_to(const Filename &other) const;
+  BLOCKING bool copy_to(const Filename &other) const;
 
   bool make_dir() const;
   bool mkdir() const;