diff --git a/test_utils.h b/test_utils.h
index 8305c14..30f1f89 100644
--- a/test_utils.h
+++ b/test_utils.h
@@ -185,7 +185,7 @@
 // This is a simple Action class for testing. It feeds an object into
 // another action.
 template<typename T>
-struct ObjectFeederAction : public Action<ObjectFeederAction<T> > {
+class ObjectFeederAction : public Action<ObjectFeederAction<T> > {
  public:
   typedef NoneType InputObjectType;
   typedef T OutputObjectType;
@@ -219,7 +219,7 @@
 // This is a simple Action class for testing. It receives an object from
 // another action.
 template<typename T>
-struct ObjectCollectorAction : public Action<ObjectCollectorAction<T> > {
+class ObjectCollectorAction : public Action<ObjectCollectorAction<T> > {
  public:
   typedef T InputObjectType;
   typedef NoneType OutputObjectType;