diff --git a/src/platform.h b/src/platform.h
index 0b327a3..306154f 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -96,9 +96,6 @@ int random();
 
 #endif  // WIN32
 
-#ifdef __HAIKU__
-#define isless(x, y) __builtin_isless(x, y)
-#endif // __HAIKU__
 
 #include "atomicops.h"
 #include "lazy-instance.h"
