diff --git a/rust.ungram b/rust.ungram
index d8950d2..1d8769f 100644
--- a/rust.ungram
+++ b/rust.ungram
@@ -58,7 +58,7 @@ ConstArg =
   Expr
 
 MacroCall =
-  Attr* Path '!' Name? TokenTree ';'?
+  Attr* Path '!' TokenTree ';'?
 
 TokenTree =
   '(' ')'
@@ -89,6 +89,7 @@ Item =
 | Fn
 | Impl
 | MacroCall
+| MacroRules
 | Module
 | Static
 | Struct
@@ -97,6 +98,14 @@ Item =
 | Union
 | Use
 
+MacroRules =
+  Attr* Visibility?
+  'macro_rules' '!' Name
+  '{' MacroArm (';' MacroArm)* ';'? '}'
+
+MacroArm =
+  TokenTree '=>' TokenTree
+
 Module =
   Attr* Visibility?
   'mod' Name