diff --git a/Scripting-faq.md b/Scripting-faq.md
index effa75b..85eccb4 100644
--- a/Scripting-faq.md
+++ b/Scripting-faq.md
@@ -11,3 +11,14 @@
 ```
 This causes a error in CRuby.
 This behavior is a limitation by the current implementation.
+
+## I can't alias for global variables.
+
+```
+> alias $a $__a__
+line 1: syntax error, unexpected tGVAR
+```
+Aliasing global variables using alias statement is out of ISO scope.
+it's mruby limitation.
+
+See also [mruby/issues#1154](https://github.com/mruby/mruby/issues/1154).
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