diff --git a/ruby.c b/ruby.c
index 991c9031de..7c6742cac4 100644
--- a/ruby.c
+++ b/ruby.c
@@ -629,7 +629,13 @@ ruby_init_loadpath(void)
 #if defined(LOAD_RELATIVE) || defined(__MACH__)
     VALUE libruby_path = runtime_libruby_path();
 # if defined(__MACH__)
-    rb_libruby_selfpath = libruby_path;
+    VALUE selfpath = libruby_path;
+#   if defined(LOAD_RELATIVE)
+    selfpath = rb_str_dup(selfpath);
+#   endif
+    rb_obj_hide(selfpath);
+    OBJ_FREEZE_RAW(selfpath);
+    rb_libruby_selfpath = selfpath;
     rb_gc_register_address(&rb_libruby_selfpath);
 # endif
 #endif