diff --git a/.env b/.env
index 7f847e29f..97f38452b 100644
--- a/.env
+++ b/.env
@@ -1,5 +1,5 @@
-DIR=`dirname $0`
-if [ -z "$VIRTUAL_ENV" ] && [ -f $DIR/../venv.mitmproxy/bin/activate ]; then
+DIR="${0%/*}"
+if [ -z "$VIRTUAL_ENV" ] && [ -f "$DIR/../venv.mitmproxy/bin/activate" ]; then
     echo "Activating mitmproxy virtualenv..."
-    source $DIR/../venv.mitmproxy/bin/activate
+    source "$DIR/../venv.mitmproxy/bin/activate"
 fi