diff --git a/ChangeLog b/ChangeLog
index ff2c1dbb1c..d8b83cd83a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Tue Nov 26 19:17:47 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* ext/objspace/object_tracing.c (newobj_i): skip class_path if class
+	  is frozen.
+
+	  rb_class_path() can modify frozen classes (and causes errors).
+	  This patch is temporary. We need no-modification/no-allocation
+	  class path function.
+
 Tue Nov 26 18:12:13 2013  Koichi Sasada  <ko1@atdot.net>
 
 	* vm_trace.c: skip "exception check" and "reentrant check (only normal
diff --git a/ext/objspace/object_tracing.c b/ext/objspace/object_tracing.c
index 2475623410..ff45172af4 100644
--- a/ext/objspace/object_tracing.c
+++ b/ext/objspace/object_tracing.c
@@ -81,7 +81,7 @@ newobj_i(VALUE tpval, void *data)
     VALUE klass = rb_tracearg_defined_class(tparg);
     struct allocation_info *info;
     const char *path_cstr = RTEST(path) ? make_unique_str(arg->str_table, RSTRING_PTR(path), RSTRING_LEN(path)) : 0;
-    VALUE class_path = RTEST(klass) ? rb_class_path(klass) : Qnil;
+    VALUE class_path = (RTEST(klass) && !OBJ_FROZEN(klass)) ? rb_class_path(klass) : Qnil;
     const char *class_path_cstr = RTEST(class_path) ? make_unique_str(arg->str_table, RSTRING_PTR(class_path), RSTRING_LEN(class_path)) : 0;
 
     if (st_lookup(arg->object_table, (st_data_t)obj, (st_data_t *)&info)) {