diff --git a/dlls/decay_gamerules.cpp b/dlls/decay_gamerules.cpp
index 1ce20bca..6cf40481 100644
--- a/dlls/decay_gamerules.cpp
+++ b/dlls/decay_gamerules.cpp
@@ -17,6 +17,7 @@
 // Author: Vyacheslav Dzhura ( slava.dzhura@gmail.com ; slava.dzhura@protonmail.com )
 // (C) 2008
 //
+#include "build.h" // for XASH_WIN32 checks
 #ifdef XASH_WIN32
 #include <windows.h>
 #else