diff --git a/dev/core/test/com/google/gwt/dev/resource/impl/ResourceAccumulatorTest.java b/dev/core/test/com/google/gwt/dev/resource/impl/ResourceAccumulatorTest.java
index 545f513..c8d6de3 100644
--- a/dev/core/test/com/google/gwt/dev/resource/impl/ResourceAccumulatorTest.java
+++ b/dev/core/test/com/google/gwt/dev/resource/impl/ResourceAccumulatorTest.java
@@ -271,8 +271,12 @@
     return list;
   }
 
-  private static PathPrefixSet createInclusivePathPrefixSet() {
-    PathPrefixSet pathPrefixes = new PathPrefixSet();
+  private PathPrefixSet pathPrefixes;
+
+  private PathPrefixSet createInclusivePathPrefixSet() {
+    // Set to a field to create a strong reference, otherwise will get GCed as ResourceAccumulator
+    // refers to it weakly.
+    pathPrefixes = new PathPrefixSet();
     pathPrefixes.add(new PathPrefix("", null));
     return pathPrefixes;
   }