diff --git a/.circleci/bootstrap-test-environment.sh b/.circleci/bootstrap-test-environment.sh
index d21e2cd1d..193a3443b 100755
--- a/.circleci/bootstrap-test-environment.sh
+++ b/.circleci/bootstrap-test-environment.sh
@@ -3,6 +3,9 @@
 PROJECT=$1
 shift
 
+EXTRA_PACKAGES=$1
+shift
+
 # Avoid the /nonexistent home directory in nobody's /etc/passwd entry.
 usermod --home /tmp/nobody nobody
 
diff --git a/.circleci/config.yml b/.circleci/config.yml
index face66f84..1acec54b1 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -227,17 +227,17 @@ jobs:
       - run:
           <<: *BOOTSTRAP_TEST_ENVIRONMENT
           command: |
-            sudo --preserve-env ~/project/.circleci/bootstrap-test-environment.sh ~/project
+            sudo ~/project/.circleci/bootstrap-test-environment.sh ~/project "${EXTRA_PACKAGES}"
 
       - run:
           <<: *SETUP_VIRTUALENV
           command: |
-            sudo --preserve-env /tmp/project/.circleci/setup-virtualenv.sh
+            sudo /tmp/project/.circleci/setup-virtualenv.sh "${TAHOE_LAFS_TOX_ENVIRONMENT}" ${TAHOE_LAFS_TOX_ARGS}
 
       - run:
           <<: *RUN_TESTS
           command: |
-            sudo --preserve-env /tmp/project/.circleci/run-tests.sh
+            sudo /tmp/project/.circleci/run-tests.sh "${TAHOE_LAFS_TOX_ENVIRONMENT}" ${TAHOE_LAFS_TOX_ARGS}
 
       - store_artifacts: *STORE_TEST_LOG
       - store_artifacts: *STORE_OTHER_ARTIFACTS
diff --git a/.circleci/run-tests.sh b/.circleci/run-tests.sh
index 6b6329e8c..9b7091269 100755
--- a/.circleci/run-tests.sh
+++ b/.circleci/run-tests.sh
@@ -1,5 +1,11 @@
 #!/bin/bash -e
 
+TAHOE_LAFS_TOX_ENVIRONMENT=$1
+shift
+
+TAHOE_LAFS_TOX_ARGS=$1
+shift
+
 # Run the test suite as a non-root user.  This is the expected usage some
 # small areas of the test suite assume non-root privileges (such as unreadable
 # files being unreadable).
@@ -7,4 +13,4 @@
 # Also run with /tmp as a workdir because the non-root user won't be able to
 # create the tox working filesystem state in the source checkout because it is
 # owned by root.
-sudo --set-home -u nobody /tmp/tests/bin/tox -c /tmp/project/tox.ini --workdir /tmp -e ${TAHOE_LAFS_TOX_ENVIRONMENT}
+sudo --set-home -u nobody /tmp/tests/bin/tox -c /tmp/project/tox.ini --workdir /tmp -e "${TAHOE_LAFS_TOX_ENVIRONMENT}" ${TAHOE_LAFS_TOX_ARGS}
diff --git a/.circleci/setup-virtualenv.sh b/.circleci/setup-virtualenv.sh
index b08272d0e..97d7825d4 100755
--- a/.circleci/setup-virtualenv.sh
+++ b/.circleci/setup-virtualenv.sh
@@ -1,5 +1,11 @@
 #!/bin/bash -e
 
+TAHOE_LAFS_TOX_ENVIRONMENT=$1
+shift
+
+TAHOE_LAFS_TOX_ARGS=$1
+shift
+
 # Set up the virtualenv as a non-root user so we can run the test suite as a
 # non-root user.  See below.
 sudo --set-home -u nobody virtualenv --python python2.7 /tmp/tests