diff --git a/src/doc/grammar.md b/src/doc/grammar.md
index 3aa89cba0314a..a09e7fad0e873 100644
--- a/src/doc/grammar.md
+++ b/src/doc/grammar.md
@@ -281,7 +281,7 @@ type_path_tail : '<' type_expr [ ',' type_expr ] + '>'
 ## Macros
 
 ```antlr
-expr_macro_rules : "macro_rules" '!' ident '(' macro_rule * ')' ';' 
+expr_macro_rules : "macro_rules" '!' ident '(' macro_rule * ')' ';'
                  | "macro_rules" '!' ident '{' macro_rule * '}' ;
 macro_rule : '(' matcher * ')' "=>" '(' transcriber * ')' ';' ;
 matcher : '(' matcher * ')' | '[' matcher * ']'