diff --git a/hash-syntax.scm b/hash-syntax.scm
index 5567753..ff55339 100644
--- a/hash-syntax.scm
+++ b/hash-syntax.scm
@@ -85,6 +85,9 @@
 (id "#i")
 (description "Inexact number [R2RS+]; n-dimensional integer vector [s7]")
 
+(id "#lang")
+(description "Declare which programming language is used [Racket]")
+
 (id "#o")
 (description "Octal integer [R2RS+]")