diff --git a/text2pcap-scanner.l b/text2pcap-scanner.l
index dd48e89997..a860df66a0 100644
--- a/text2pcap-scanner.l
+++ b/text2pcap-scanner.l
@@ -43,6 +43,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#ifdef _WIN32
+#include <io.h>  /* for isatty() */
+#endif
+
 #include "text2pcap.h"
 
 /*