diff --git a/app-gradle-plugin/src/integTest/java/com/google/cloud/tools/gradle/appengine/sourcecontext/SourceContextPluginIntegrationTest.java b/app-gradle-plugin/src/integTest/java/com/google/cloud/tools/gradle/appengine/sourcecontext/SourceContextPluginIntegrationTest.java
index dce91ec30..942166db1 100644
--- a/app-gradle-plugin/src/integTest/java/com/google/cloud/tools/gradle/appengine/sourcecontext/SourceContextPluginIntegrationTest.java
+++ b/app-gradle-plugin/src/integTest/java/com/google/cloud/tools/gradle/appengine/sourcecontext/SourceContextPluginIntegrationTest.java
@@ -64,6 +64,9 @@ public void setUpTestProject() throws IOException {
       while (entries.hasMoreElements()) {
         ZipEntry entry = entries.nextElement();
         File entryDestination = new File(testProjectDir.getRoot(), entry.getName());
+        if (!entryDestination.toPath().normalize().startsWith(testProjectDir.getRoot().toPath())) {
+          throw new RuntimeException("Bad zip entry");
+        }
         if (entry.isDirectory()) {
           entryDestination.mkdirs();
         } else {