diff --git a/collects/parser-tools/lex.ss b/collects/parser-tools/lex.ss
index 67d934d..91c5fcd 100644
--- a/collects/parser-tools/lex.ss
+++ b/collects/parser-tools/lex.ss
@@ -121,7 +121,7 @@
                        ;; including the one just read
                        (length 1)
                        ;; how many characters are in the longest match
-                       (longest-match-length 0))
+                       (longest-match-length 1))
         (let ((next-state
                (cond
                  ((eof-object? char)