diff --git a/mps/tool/testrun.sh b/mps/tool/testrun.sh
index cdb41ac458b..f44b74217e2 100755
--- a/mps/tool/testrun.sh
+++ b/mps/tool/testrun.sh
@@ -24,8 +24,12 @@
 
 # Make a temporary output directory for the test logs.
 LOGDIR=$(mktemp -d /tmp/mps.log.XXXXXX)
+TEST_DIR=$1
 echo "MPS test suite"
 echo "Logging test output to $LOGDIR"
+echo "Test directory: $TEST_DIR"
+shift
+TEST_CASES=${*:-${ALL_TEST_CASES}}
 
 # First argument is the directory containing the test cases.
 TEST_DIR=$1