diff --git a/src/stdafx.h b/src/stdafx.h
--- a/src/stdafx.h
+++ b/src/stdafx.h
@@ -438,9 +438,6 @@ void NORETURN CDECL error(const char *st
 /* Asserts are enabled if NDEBUG isn't defined or WITH_ASSERT is defined. */
 #if !defined(NDEBUG) || defined(WITH_ASSERT)
 #	define OTTD_ASSERT
-#	define assert_msg(expression, msg, ...) if (unlikely(!(expression))) error("Assertion failed at line %i of %s: %s\n\t" msg, __LINE__, __FILE__, #expression, __VA_ARGS__);
-#else
-#	define assert_msg(expression, msg, ...)
 #endif
 
 #if defined(OPENBSD)