diff --git a/crates/wasm/js-tests/firefox-env b/crates/wasm/js-tests/firefox-env
index 62e7ef72..d9f99c04 100644
--- a/crates/wasm/js-tests/firefox-env
+++ b/crates/wasm/js-tests/firefox-env
@@ -4,7 +4,9 @@ if [ ! -d zotero-standalone-build/xulrunner ]; then
   echo "error: could not find Firefox in $PWD/zotero-standalone-build/xulrunner" >/dev/stderr
   exit 1
 fi
-. "./zotero-standalone-build/config.sh"
+
+cd zotero-standalone-build
+. "./config.sh"
 
 UNAME=$(uname)
 if [ "$UNAME" = "Linux" ]; then