diff --git a/pom.xml b/pom.xml
index 17a9ac9ca..0f92b680f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -935,7 +935,8 @@
       </activation>
       <properties>
         <!-- LANG-1265: allow tests to access private fields/methods of java.base classes via reflection -->
-        <argLine>-Xmx512m --add-opens java.base/java.lang.reflect=ALL-UNNAMED --add-opens java.base/java.lang=ALL-UNNAMED</argLine>
+        <!-- LANG-1667: allow tests to access private fields/methods of java.base/java.util such as ArrayList via reflection -->
+        <argLine>-Xmx512m --add-opens java.base/java.lang.reflect=ALL-UNNAMED --add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/java.util=ALL-UNNAMED</argLine>
         <!-- coverall version 4.3.0 does not work with java 9, see https://github.com/trautonen/coveralls-maven-plugin/issues/112 -->
         <coveralls.skip>true</coveralls.skip>
       </properties>