diff --git a/src/scanner.l b/src/scanner.l
index b2fd97d..89c93fd 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -18,6 +18,7 @@
  */
 
 %option yylineno
+%option never-interactive
 
 %{
 /* scanner for security protocols language */