diff --git a/test/run-tests.sh b/test/run-tests.sh
index 778d3aa..d26c111 100755
--- a/test/run-tests.sh
+++ b/test/run-tests.sh
@@ -320,7 +320,7 @@ if [[ $# -gt 0 && $1 != -* ]]; then
     if [[ $command == eval ]]; then
         command=evalTest
     fi
-    : ${scenario:=default}
+    : "${scenario:=default}"
 elif [[ $scenario ]]; then
     command=buildTest
 else