diff --git a/custodia.spec b/custodia.spec
index bbc00f6..a66bc45 100644
--- a/custodia.spec
+++ b/custodia.spec
@@ -12,7 +12,7 @@
 
 Name:           custodia
 Version:        0.5.0
-Release:        7%{?dist}
+Release:        8%{?dist}
 Summary:        A service to manage, retrieve and store secrets for other processes
 
 License:        GPLv3+
@@ -161,6 +161,9 @@ Sub-package with python3 custodia extra modules (etcdstore)
 export PIP_INDEX_URL=http://host.invalid./
 # Don't try to download dnspython3. The package is provided by python%{python3_pkgversion}-dns
 export PIP_NO_DEPS=yes
+# Ignore all install packages to enforce installation of sdist. Otherwise tox
+# may pick up this package from global site-packages instead of source dist.
+export PIP_IGNORE_INSTALLED=yes
 
 tox --sitepackages -e py%{python2_version_nodots} -- --skip-servertests
 %if 0%{?with_python3}
@@ -276,6 +279,9 @@ exit 0
 
 
 %changelog
+* Wed Aug 02 2017 Christian Heimes <cheimes@redhat.com> - 0.5.0-8
+- Add PIP_IGNORE_INSTALLED
+
 * Tue Aug 01 2017 Christian Heimes <cheimes@redhat.com> - 0.5.0-7
 - Modernize spec
 
@@ -283,7 +289,7 @@ exit 0
 - Require latest python-jwcrypto with Python 3 fix
 - Use python2 prefix for all Python 2 dependencies
 
-* Mon Jul 03 2017 Christian Heimes <cheimes@redhat.com> - 0.5.0-5
+* Tue Aug 01 2017 Christian Heimes <cheimes@redhat.com> - 0.5.0-5
 - Add custodia user and named systemd instances
 
 * Wed Jul 26 2017 Fedora Release Engineering <releng@fedoraproject.org> - 0.5.0-4