diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 312b7e4..dbc436e 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -38,6 +38,7 @@
     virtualenv $VENV_DIR
     source ${VENV_DIR}/bin/activate
     pip install salt${PIP_SALT_VERSION}
+    pip install 'msgpack<1.0.0'
 }
 
 setup_pillar() {