diff --git a/web_server.h b/web_server.h
index 1bf4d1c08e60ddcbc851d222b939308515dc2b03..d453e63fa404f025b85e98ad8dee4538bac364cf 100644
--- a/web_server.h
+++ b/web_server.h
@@ -9,7 +9,9 @@
 #include "config.h"
 #include "util.h"
 #include "co2_sensor.h"
-#include "csv_writer.h"
+#ifdef CSV_WRITER
+#  include "csv_writer.h"
+#endif
 #ifdef MQTT
 #  include "mqtt.h"
 #endif