diff --git a/Lib/plat-mac/bundlebuilder.py b/Lib/plat-mac/bundlebuilder.py
index a90a194..d8c5557 100755
--- a/Lib/plat-mac/bundlebuilder.py
+++ b/Lib/plat-mac/bundlebuilder.py
@@ -255,10 +255,10 @@
 #!/bin/sh
 
 execdir=$(dirname "${0}")
-executable=${execdir}/%(executable)s
+executable="${execdir}/%(executable)s"
 resdir=$(dirname "${execdir}")/Resources
-main=${resdir}/%(mainprogram)s
-PYTHONPATH=$resdir
+main="${resdir}/%(mainprogram)s"
+PYTHONPATH="$resdir"
 export PYTHONPATH
 exec "${executable}" "${main}" "${1}"
 """