diff --git a/Mac/IDLE/Makefile.in b/Mac/IDLE/Makefile.in
index c06ca06b889..1fd30a7d17b 100644
--- a/Mac/IDLE/Makefile.in
+++ b/Mac/IDLE/Makefile.in
@@ -42,7 +42,7 @@ IDLE.app:  \
 		$(srcdir)/../Icons/PythonSource.icns \
 		$(srcdir)/../Icons/PythonCompiled.icns Info.plist
 	rm -fr IDLE.app
-	$(RUNSHARED) arch -ppc -i386 $(BUILDPYTHON) $(BUNDLEBULDER) \
+	$(RUNSHARED) @ARCH_RUN_32BIT@ $(BUILDPYTHON) $(BUNDLEBULDER) \
 		--builddir=. \
 		--name=IDLE \
 		--link-exec \