Index: tools/ddbg.cpp
--- tools/ddbg.cpp.orig
+++ tools/ddbg.cpp
@@ -6,6 +6,7 @@
 #include <cstdio>
 #include <string>
 #include <string_view>
+#include <unistd.h>
 #include <libHX/io.h>
 #include <libHX/option.h>
 #include <libHX/scope.hpp>
