diff --git a/btui.h b/btui.h
index 226e8be..edf1db0 100644
--- a/btui.h
+++ b/btui.h
@@ -18,6 +18,8 @@
 #include <time.h>
 #include <unistd.h>
 
+#define BTUI_VERSION 1
+
 typedef struct {
     FILE *in, *out;
     int width, height;