diff --git a/Makefile.pre.in b/Makefile.pre.in
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1000,12 +1000,12 @@
 		$(INSTALL_DATA) $(srcdir)/Modules/xxmodule.c \
 			$(DESTDIR)$(LIBDEST)/distutils/tests ; \
 	fi
-	PYTHONPATH=$(DESTDIR)$(LIBDEST)  $(RUNSHARED) \
+	-PYTHONPATH=$(DESTDIR)$(LIBDEST)  $(RUNSHARED) \
 		$(PYTHON_FOR_BUILD) -Wi -tt $(DESTDIR)$(LIBDEST)/compileall.py \
 		-d $(LIBDEST) -f \
 		-x 'bad_coding|badsyntax|site-packages|lib2to3/tests/data' \
 		$(DESTDIR)$(LIBDEST)
-	PYTHONPATH=$(DESTDIR)$(LIBDEST) $(RUNSHARED) \
+	-PYTHONPATH=$(DESTDIR)$(LIBDEST) $(RUNSHARED) \
 		$(PYTHON_FOR_BUILD) -Wi -tt -O $(DESTDIR)$(LIBDEST)/compileall.py \
 		-d $(LIBDEST) -f \
 		-x 'bad_coding|badsyntax|site-packages|lib2to3/tests/data' \
