diff -Naur openttd-1.11.0/src/cpu.cpp openttd-1.11.0.serenity/src/cpu.cpp
--- openttd-1.11.0/src/cpu.cpp	2021-04-22 01:14:21.038920133 +0200
+++ openttd-1.11.0.serenity/src/cpu.cpp	2021-04-22 01:13:56.638440518 +0200
@@ -40,7 +40,7 @@
 #endif
 
 /* rdtsc for all other *nix-en (hopefully). Use GCC syntax */
-#if (defined(__i386__) || defined(__x86_64__)) && !defined(RDTSC_AVAILABLE)
+#if (defined(__i386__) || defined(__x86_64__)) && !defined(__serenity__) && !defined(RDTSC_AVAILABLE)
 uint64 ottd_rdtsc()
 {
 	uint32 high, low;