--- a/main.c
+++ b/main.c
@@ -33,6 +33,11 @@
 #include <ncurses.h>
 #endif
 
+// musl has no this constant
+#ifndef TCPI_OPT_SYN_DATA
+#define TCPI_OPT_SYN_DATA 32
+#endif
+
 #include "gen.h"
 #include "help.h"
 #include "colors.h"