diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e5480de0c25b..cc719b383f0d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2003-12-21  Roger Sayle  <roger@eyesopen.com>
+
+	* config/ia64/hpux.h (TARGET_OS_CPP_BUILTINS): Define _ILP32
+	when compiling in ILP32 mode.
+
 2003-12-21  Andrew Pinski  <pinskia@physics.uc.edu>
 
 	* config/rs6000/rs6000.c (rs6000_tls_referenced_p): Return early if
diff --git a/gcc/config/ia64/hpux.h b/gcc/config/ia64/hpux.h
index 7ed5f605590e..1bd02c35d730 100644
--- a/gcc/config/ia64/hpux.h
+++ b/gcc/config/ia64/hpux.h
@@ -45,6 +45,8 @@ do {							\
 	    builtin_define("_HPUX_SOURCE");		\
 	    builtin_define("__STDC_EXT__");		\
 	  }						\
+	if (TARGET_ILP32)				\
+	  builtin_define("_ILP32");			\
 } while (0)
 
 #undef CPP_SPEC