diff --git a/build/build.xml b/build/build.xml
index cee8160eff..bb88bd3cfa 100644
--- a/build/build.xml
+++ b/build/build.xml
@@ -170,7 +170,7 @@
 			checkreturn="true" />
 
 		<!-- Install composer dependencies, if there are any. -->
-		<exec dir="."
+		<exec dir="${dir}"
 			command='php -r "\$j = json_decode(file_get_contents(\"composer.json\")); echo isset(\$j->require);"'
 			checkreturn="true"
 			outputProperty='composer-has-dependencies' />