diff --git a/src/demo/demo.c b/src/demo/demo.c
index ddf054516..dca502716 100644
--- a/src/demo/demo.c
+++ b/src/demo/demo.c
@@ -8,6 +8,7 @@
 #include <getopt.h>
 #include <stdlib.h>
 #include <stdatomic.h>
+#include <errno.h>
 #include "demo.h"
 
 // (non-)ansi terminal definition-4-life