diff --git a/ext/v8/v8_cxt.cpp b/ext/v8/v8_cxt.cpp
index 07f4043..1f22a10 100644
--- a/ext/v8/v8_cxt.cpp
+++ b/ext/v8/v8_cxt.cpp
@@ -72,7 +72,7 @@ namespace {
   }
   VALUE SetData(VALUE self, VALUE data) {
     HandleScope scope;
-    unwrap(self)->SetData(rr_rb2v8(data));
+    unwrap(self)->SetData(rr_rb2v8(data)->ToString());
     return Qnil;
   }
 }