diff --git a/peps/pep-0508.rst b/peps/pep-0508.rst
index 71f4648194e..849bf49ba04 100644
--- a/peps/pep-0508.rst
+++ b/peps/pep-0508.rst
@@ -453,10 +453,10 @@ The complete parsley grammar::
     pchar         = unreserved | pct_encoded | sub_delims | ':' | '@'
     query         = ( pchar | '/' | '?')*
     fragment      = ( pchar | '/' | '?')*
-    pct_encoded   = '%' hexdig
+    pct_encoded   = '%' hexdig{2}
     unreserved    = letter | digit | '-' | '.' | '_' | '~'
     reserved      = gen_delims | sub_delims
-    gen_delims    = ':' | '/' | '?' | '#' | '(' | ')?' | '@'
+    gen_delims    = ':' | '/' | '?' | '#' | '[' | ']' | '@'
     sub_delims    = '!' | '$' | '&' | '\\'' | '(' | ')' | '*' | '+' | ',' | ';' | '='
     hexdig        = digit | 'a' | 'A' | 'b' | 'B' | 'c' | 'C' | 'd' | 'D' | 'e' | 'E' | 'f' | 'F'