diff --git a/proposal/mutant/src/java/bootstrap/org/apache/ant/builder/Builder.java b/proposal/mutant/src/java/bootstrap/org/apache/ant/builder/Builder.java
index 061f796e5..53b088d30 100644
--- a/proposal/mutant/src/java/bootstrap/org/apache/ant/builder/Builder.java
+++ b/proposal/mutant/src/java/bootstrap/org/apache/ant/builder/Builder.java
@@ -135,6 +135,7 @@ public class Builder {
         files.add(new File(UTIL_ROOT, "regexp/RegexpFactory.java"));
         files.add(new File(UTIL_ROOT, "regexp/RegexpMatcherFactory.java"));
         files.add(new File(TYPES_ROOT, "Commandline.java"));
+        files.add(new File(UTIL_ROOT, "JavaEnvUtils.java"));
         files.add(new File(PACKAGE_ROOT, "BuildException.java"));
         files.add(new File(PACKAGE_ROOT, "Location.java"));
         files.add(new File(PACKAGE_ROOT, "AntClassLoader.java"));