diff --git a/sim/ppc/ChangeLog b/sim/ppc/ChangeLog
index a50f266015..b7ff467869 100644
--- a/sim/ppc/ChangeLog
+++ b/sim/ppc/ChangeLog
@@ -1,10 +1,11 @@
 2009-09-15  Andreas Tobler <andreast-list@fgznet.ch>
 	    Doug Evans  <dje@google.com>
 
-	* configure.ac (sim_hwflags): Clean up definition, AC_SUBST it.
+	* configure.ac (sim_hwflags): Use AC_DEFINE to define HAVE_UNION_SEMUN.
 	* configure: Regenerate.
-	* Makefile.in (SIM_HWFLAGS): New variable.
-	(STD_CFLAGS, NOWARN_CFLAGS): Add it.
+	* config.in: Regenerate.
+	* hw_sem.c: #include "config.h".
+	(HAVE_UNION_SEMUN): Renamed from HAS_UNION_SEMUN.
 
 2009-08-22  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
diff --git a/sim/ppc/Makefile.in b/sim/ppc/Makefile.in
index db7ff1b96c..71c65cf826 100644
--- a/sim/ppc/Makefile.in
+++ b/sim/ppc/Makefile.in
@@ -70,7 +70,6 @@ MAKEINFO = makeinfo
 RANLIB = @RANLIB@
 
 SIM_CFLAGS = @sim_cflags@
-SIM_HWFLAGS = @sim_hwflags@
 INLINE_CFLAGS = @sim_inline@
 BSWAP_CFLAGS = @sim_bswap@
 ENDIAN_CFLAGS = @sim_endian@
@@ -117,8 +116,8 @@ CONFIG_CFLAGS = $(BSWAP_CFLAGS) \
   $(DEVZERO_CFLAGS)
 SIM_FPU_CFLAGS = @sim_fpu_cflags@
 
-STD_CFLAGS	= $(CFLAGS) $(INLINE_CFLAGS) $(CONFIG_CFLAGS) $(WARNING_CFLAGS) $(SIM_CFLAGS) $(HDEFINES) $(TDEFINES) $(INCLUDES) $(INTL_CFLAGS) $(SIM_FPU_CFLAGS) $(SIM_HWFLAGS)
-NOWARN_CFLAGS	= $(CFLAGS) $(INLINE_CFLAGS) $(CONFIG_CFLAGS) $(SIM_CFLAGS) $(HDEFINES) $(TDEFINES) $(INCLUDES)  $(SIM_FPU_CFLAGS) $(SIM_HWFLAGS)
+STD_CFLAGS	= $(CFLAGS) $(INLINE_CFLAGS) $(CONFIG_CFLAGS) $(WARNING_CFLAGS) $(SIM_CFLAGS) $(HDEFINES) $(TDEFINES) $(INCLUDES) $(INTL_CFLAGS) $(SIM_FPU_CFLAGS)
+NOWARN_CFLAGS	= $(CFLAGS) $(INLINE_CFLAGS) $(CONFIG_CFLAGS) $(SIM_CFLAGS) $(HDEFINES) $(TDEFINES) $(INCLUDES)  $(SIM_FPU_CFLAGS)
 BUILD_CFLAGS	= $(CFLAGS_FOR_BUILD) $(INCLUDES) $(WARNING_CFLAGS)
 
 BUILD_LDFLAGS	=
diff --git a/sim/ppc/config.in b/sim/ppc/config.in
index 5a1dc05a8e..86a6825ea0 100644
--- a/sim/ppc/config.in
+++ b/sim/ppc/config.in
@@ -272,6 +272,9 @@
 /* Define to 1 if you have the `umask' function. */
 #undef HAVE_UMASK
 
+/* Define if union semun is defined in <sys/sem.h> */
+#undef HAVE_UNION_SEMUN
+
 /* Define to 1 if you have the <unistd.h> header file. */
 #undef HAVE_UNISTD_H
 
diff --git a/sim/ppc/configure b/sim/ppc/configure
index 872a9db050..abdfdb2015 100755
--- a/sim/ppc/configure
+++ b/sim/ppc/configure
@@ -589,7 +589,6 @@ ac_includes_default="\
 #endif"
 
 ac_subst_vars='LTLIBOBJS
-sim_hwflags
 sim_fpu
 sim_fpu_cflags
 sim_targ_vals
@@ -3741,9 +3740,9 @@ else
 fi
 
 if test x"$ac_cv_has_union_semun" = x"yes" -a x"$ac_cv_sysv_sem" = x"yes" ; then
-  sim_hwflags="-DHAS_UNION_SEMUN"
-else
-  sim_hwflags=""
+
+$as_echo "#define HAVE_UNION_SEMUN 1" >>confdefs.h
+
 fi
 
 
@@ -6011,7 +6010,6 @@ fi
 
 
 
-
 
 
 ac_config_files="$ac_config_files Makefile"
diff --git a/sim/ppc/configure.ac b/sim/ppc/configure.ac
index 2dc200caa7..e8ccfe97da 100644
--- a/sim/ppc/configure.ac
+++ b/sim/ppc/configure.ac
@@ -301,9 +301,8 @@ else
 fi
 
 if test x"$ac_cv_has_union_semun" = x"yes" -a x"$ac_cv_sysv_sem" = x"yes" ; then
-  sim_hwflags="-DHAS_UNION_SEMUN"
-else
-  sim_hwflags=""
+  AC_DEFINE(HAVE_UNION_SEMUN, 1,
+	    [Define if union semun is defined in <sys/sem.h>])
 fi
 
 
@@ -903,7 +902,6 @@ AC_SUBST(sim_callback)
 AC_SUBST(sim_targ_vals)
 AC_SUBST(sim_fpu_cflags)
 AC_SUBST(sim_fpu)
-AC_SUBST(sim_hwflags)
 
 AC_OUTPUT(Makefile,
 [case x$CONFIG_HEADERS in xconfig.h:config.in) echo > stamp-h ;; esac])
diff --git a/sim/ppc/hw_sem.c b/sim/ppc/hw_sem.c
index 28e0c17f42..a7d618b31b 100644
--- a/sim/ppc/hw_sem.c
+++ b/sim/ppc/hw_sem.c
@@ -100,7 +100,7 @@ typedef struct _hw_sem_device {
   int count;
 } hw_sem_device;
 
-#if !HAS_UNION_SEMUN
+#ifndef HAVE_UNION_SEMUN
 union semun {
   int val;
   struct semid_ds *buf;