diff --git a/run_unit_tests.sh b/run_unit_tests.sh
index 84150d0..7d8c950 100755
--- a/run_unit_tests.sh
+++ b/run_unit_tests.sh
@@ -15,6 +15,9 @@
 
 export SCRIPT_DIR=$(cd `dirname $0` && pwd -P)
 source $SCRIPT_DIR/functions
+if [ "4.8" != "latest" ]; then
+   export PUPPET_GEM_VERSION='~> 4.8.0'
+fi
 
 install_module