diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 9761585..0ab7d81 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -39,7 +39,7 @@
     log_info "Setting up Python virtualenv"
     virtualenv $VENV_DIR
     source ${VENV_DIR}/bin/activate
-    python -m pip install salt${PIP_SALT_VERSION}
+    python -m pip install salt${PIP_SALT_VERSION} 'msgpack<1'
 }
 
 setup_mock_bin() {