diff --git a/Makefile b/Makefile
index 338a121..542ace3 100644
--- a/Makefile
+++ b/Makefile
@@ -30,7 +30,7 @@ upgrade: $(COMMON_CONSTRAINTS_TXT)
 	pip-compile --upgrade -o requirements/pip-tools.txt requirements/pip-tools.in
 	pip install -qr requirements/pip.txt
 	pip install -qr requirements/pip-tools.txt
-	pip-compile --upgrade -o requirements/base.txt requirements/base.in
+	pip-compile --upgrade --allow-unsafe -o requirements/base.txt requirements/base.in
 	pip-compile --upgrade -o test-requirements.txt requirements/test.in
 	# Let tox control the Django version for tests
 	sed -i.tmp '/^django==/d' test-requirements.txt