diff --git a/mozilla/xpcom/typelib/xpidl/xpidl_idl.c b/mozilla/xpcom/typelib/xpidl/xpidl_idl.c
index 5f855f786fb..76008d3a1e4 100644
--- a/mozilla/xpcom/typelib/xpidl/xpidl_idl.c
+++ b/mozilla/xpcom/typelib/xpidl/xpidl_idl.c
@@ -248,7 +248,7 @@ NextIsRaw(struct input_callback_data *data, char **startp, int *lenp)
         *lenp = end - data->point + 2;
         data->f_raw = 0;
     } else {
-        *lenp = data->len;
+        *lenp = data->buf + data->len - data->point;
         data->f_raw = 1;
     }
     return 1;