diff --git a/build.xml b/build.xml
index a670496b7b..ee2df209fd 100644
--- a/build.xml
+++ b/build.xml
@@ -1286,7 +1286,7 @@ under the License.
                fork="true"
                modulepath="${basedir}/lib/main-tests"
                unless:true="${isJava8}">
-            <compilerarg line="--patch-module org.apache.poi.ooxml_lite=${ooxml.output.test.dir}:${ooxml.lite.output.dir}"/>
+            <compilerarg line="--patch-module org.apache.poi.ooxml_lite=${ooxml.output.test.dir}${path.separator}${ooxml.lite.output.dir}"/>
         </javac>
 
         <jar destfile="${ooxml.lite.agent}">