diff --git a/pages/common/lex.md b/pages/common/lex.md
index aba6bff4d3..1972f72159 100644
--- a/pages/common/lex.md
+++ b/pages/common/lex.md
@@ -7,6 +7,10 @@
 
 `lex {{analyser.l}}`
 
+- Specify the output file:
+
+`lex {{analyser.l}} --outfile {{analyser.c}}
+
 - Compile a C file generated by lex:
 
 `cc {{path/to/lex.yy.c}} --output {{executable}}`