diff --git a/parser/src/earley/parser.rs b/parser/src/earley/parser.rs
index 33e37a1..0bec6b9 100644
--- a/parser/src/earley/parser.rs
+++ b/parser/src/earley/parser.rs
@@ -1496,11 +1496,15 @@ impl ParserState {
         }
     }
 
-    /// Advance the parser with given lexeme_idx.
-    /// lexer_state is state *after* consuming the byte.
-    /// It either initial lexer states for lazy lexers,
-    /// or lexer_initial_state+byte for greedy lexers.
-    /// lexer_byte is the byte that led to producing the lexeme.
+
+    /// Advance the parser with given 'pre_lexeme'.
+    /// On return, the lexer_state will be the state *after* consuming
+    /// 'pre_lexeme'.  As a special case, a following single byte lexeme
+    /// is also consumed.
+    ///
+    // The new lexer state will be an initial lexer states when the lexing
+    // is lazy.  If the lexing was greedy, it will be an initial lexer state
+    // advanced to the byte which produced the greedy lexeme.
 
     // This is never inlined anyways, so better make it formal
     #[inline(never)]