diff --git a/include/sys/isa_defs.h b/include/sys/isa_defs.h
index 49fe773d4..7e15b9321 100644
--- a/include/sys/isa_defs.h
+++ b/include/sys/isa_defs.h
@@ -118,10 +118,6 @@
 #define __sparc__
 #endif
 
-#if !defined(_ILP32)
-#define _ILP32
-#endif
-
 #if defined(__arch64__)
 #if !defined(_LP64)
 #define _LP64