diff --git a/Eigen/src/Core/util/Meta.h b/Eigen/src/Core/util/Meta.h
index 29c149c34..e5e1b760f 100755
--- a/Eigen/src/Core/util/Meta.h
+++ b/Eigen/src/Core/util/Meta.h
@@ -381,13 +381,12 @@ struct has_ReturnType
   enum { value = sizeof(testFunctor<T>(0)) == sizeof(meta_yes) };
 };
 
-template<int Size> struct meta_array { int a[Size]; };
 template<typename T> const T& return_ref();
 
 template <typename T>
 struct has_nullary_operator
 {
-  template <typename C> static meta_yes testFunctor(C const *,meta_array< sizeof(return_ref<C>()()) > * = 0);
+  template <typename C> static meta_yes testFunctor(C const *,enable_if<(sizeof(return_ref<C>()())>0)> * = 0);
   static meta_no testFunctor(...);
 
   enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) };
@@ -396,7 +395,7 @@ struct has_nullary_operator
 template <typename T>
 struct has_unary_operator
 {
-  template <typename C> static meta_yes testFunctor(C const *,meta_array< sizeof(return_ref<C>()(Index(0))) > * = 0);
+  template <typename C> static meta_yes testFunctor(C const *,enable_if<(sizeof(return_ref<C>()(Index(0)))>0)> * = 0);
   static meta_no testFunctor(...);
 
   enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) };
@@ -405,7 +404,7 @@ struct has_unary_operator
 template <typename T>
 struct has_binary_operator
 {
-  template <typename C> static meta_yes testFunctor(C const *,meta_array< sizeof(return_ref<C>()(Index(0),Index(0))) > * = 0);
+  template <typename C> static meta_yes testFunctor(C const *,enable_if<(sizeof(return_ref<C>()(Index(0),Index(0)))>0)> * = 0);
   static meta_no testFunctor(...);
 
   enum { value = sizeof(testFunctor(static_cast<T*>(0))) == sizeof(meta_yes) };