Index: src/platform.h
==================================================================
--- src/platform.h
+++ src/platform.h
@@ -155,10 +155,12 @@
 # define OF_ACORN_RISC_OS
 #elif defined(__MINT__)
 # define OF_MINT
 #elif defined(__gnu_hurd__)
 # define OF_HURD
+#elif defined(__serenity__)
+# define OF_SERENITYOS
 #endif
 
 #ifdef __GLIBC__
 # define OF_GLIBC
 #endif