diff --git a/playbooks/requirements-integration-dsvm/run.yaml b/playbooks/requirements-integration-dsvm/run.yaml
index faab42131b..157bd9a0e1 100644
--- a/playbooks/requirements-integration-dsvm/run.yaml
+++ b/playbooks/requirements-integration-dsvm/run.yaml
@@ -122,6 +122,7 @@
           export DEVSTACK_GATE_EXERCISES=0
           export DEVSTACK_GATE_REQS_INTEGRATION=1
           export PIP_PROCESS_DEPENDENCY_LINKS=1
+          export USE_PYTHON3=true
           function gate_hook {
               set -x
               bash $BASE/new/devstack-gate/devstack-vm-gate.sh && \
diff --git a/tox.ini b/tox.ini
index 22db546649..d9effdfaf7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,7 +7,7 @@ ignore_basepython_conflict=true
 [testenv]
 basepython = python3
 usedevelop = True
-install_command = pip install -U {opts} {packages}
+install_command = pip install -U {opts} -c {toxinidir}/upper-constraints.txt {packages}
 setenv = VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
@@ -16,13 +16,11 @@ commands =
 
 [testenv:py27-check-uc]
 basepython = python2.7
-install_command = pip install -U {opts} -c {toxinidir}/upper-constraints.txt {packages}
 deps = -r{toxinidir}/upper-constraints.txt
 commands = check-conflicts {toxinidir}/upper-constraints.txt {toxinidir}/upper-constraints-xfails.txt
 
 [testenv:py36-check-uc]
 basepython = python3.6
-install_command = pip install -U {opts} -c {toxinidir}/upper-constraints.txt {packages}
 deps = -r{toxinidir}/upper-constraints.txt
 commands = check-conflicts {toxinidir}/upper-constraints.txt {toxinidir}/upper-constraints-xfails.txt
 
@@ -33,6 +31,10 @@ commands = {posargs}
 commands = update-requirements {posargs}
 
 [testenv:generate]
+# Generate needs an unconstrained install to get new dependencies
+install_command = pip install -U {opts} {packages}
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
 commands = generate-constraints {posargs}
 
 [testenv:validate]
@@ -88,7 +90,6 @@ commands =
 [testenv:babel]
 # Use the local upper-constraints.txt file
 deps = Babel
-install_command = pip install -c upper-constraints.txt {opts} {packages}
 commands = {toxinidir}/tools/babel-test.sh
 
 [flake8]