diff --git a/src/precompiled_header.hpp b/src/precompiled_header.hpp
index 89f032be6..6aa6ae57b 100644
--- a/src/precompiled_header.hpp
+++ b/src/precompiled_header.hpp
@@ -152,4 +152,9 @@
 #include <unordered_map>
 #include <unordered_set>
 #include <vector>
+
+#ifndef UNUSED
+#define UNUSED(x) (void)(x)
+#endif
+
 #endif