diff --git a/tests/bin/docker-tests.sh b/tests/bin/docker-tests.sh
index 7589ff792..eff259574 100755
--- a/tests/bin/docker-tests.sh
+++ b/tests/bin/docker-tests.sh
@@ -67,6 +67,18 @@ main() {
 
     local SCITRAN_CORE_DRONE_SECRET="secret"
 
+    # Clean dev/test artifacts like pyc files and coverage reports
+    # Run within container to avoid permission problems
+    docker run --rm \
+        --name core-test-cleanup \
+        --volume $(pwd):/src/core \
+        scitran/core:testing \
+        sh -c '
+            find . -type d -name __pycache__ -exec rm -rf {}\;;
+            find . -type f -name "*.pyc" -delete;
+            rm -rf .coverage htmlcov;
+        '
+
     # Launch core + mongo
     docker run -d \
         --name core-test-service \
@@ -114,7 +126,6 @@ clean_up() {
             --volume $(pwd):/src/core \
             scitran/core:testing \
             sh -c '
-                rm -rf .coverage htmlcov;
                 coverage combine;
                 coverage report --skip-covered --show-missing;
                 coverage html;
diff --git a/tests/bin/tests.sh b/tests/bin/tests.sh
index 55538d2cc..7c7607562 100755
--- a/tests/bin/tests.sh
+++ b/tests/bin/tests.sh
@@ -33,6 +33,7 @@ Envvars (required for integration tests):
 
 
 main() {
+    export PYTHONDONTWRITEBYTECODE=1
     export RUN_ALL=true
     local RUN_LINT=false
     local RUN_UNIT=false
@@ -94,12 +95,12 @@ main() {
     if ${RUN_UNIT}; then
         log "Running unit tests ..."
         rm -f .coverage
-        PYTHONDONTWRITEBYTECODE=1 py.test --cov=api --cov-report= tests/unit_tests/python $PYTEST_ARGS
+        py.test --cov=api --cov-report= tests/unit_tests/python $PYTEST_ARGS
     fi
 
     if ${RUN_INTEG}; then
         log "Running integration tests ..."
-        PYTHONDONTWRITEBYTECODE=1 py.test tests/integration_tests/python $PYTEST_ARGS
+        py.test tests/integration_tests/python $PYTEST_ARGS
     fi
 }