diff --git a/tox.ini b/tox.ini
index 28af1e87..2d1bec8d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -17,7 +17,7 @@ whitelist_externals = find
                       make
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-install_command = pip install -U {opts} {packages}
+install_command = pip install -c ./upper-constraints.txt -U {opts} {packages}
 usedevelop = True
 commands =
   find . -type f -name "*.pyc" -delete
diff --git a/upper-constraints.txt b/upper-constraints.txt
index 8b8e2bc4..79962df3 100644
--- a/upper-constraints.txt
+++ b/upper-constraints.txt
@@ -43,3 +43,13 @@ requests===2.18.4
 six===1.11.0
 SQLAlchemy===1.1.14
 virtualenv===15.1.0
+
+
+# testing
+
+pytest===3.3.0
+pytest-cov===2.5.1
+pytest-forked===0.2
+pytest-html===1.16.0
+pytest-metadata===1.5.1
+pytest-xdist===1.20.1