diff --git a/Eigen/src/Core/Diagonal.h b/Eigen/src/Core/Diagonal.h
index c62f5ff21..563135fb2 100644
--- a/Eigen/src/Core/Diagonal.h
+++ b/Eigen/src/Core/Diagonal.h
@@ -70,7 +70,10 @@ template<typename MatrixType, int _DiagIndex> class Diagonal
     EIGEN_DENSE_PUBLIC_INTERFACE(Diagonal)
 
     EIGEN_DEVICE_FUNC
-    explicit inline Diagonal(MatrixType& matrix, Index a_index = DiagIndex) : m_matrix(matrix), m_index(a_index) {}
+    explicit inline Diagonal(MatrixType& matrix, Index a_index = DiagIndex) : m_matrix(matrix), m_index(a_index)
+    {
+      eigen_assert( a_index <= m_matrix.cols() && -a_index <= m_matrix.rows() );
+    }
 
     EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Diagonal)
 
diff --git a/test/diagonal.cpp b/test/diagonal.cpp
index c1546e97d..0b5ae8280 100644
--- a/test/diagonal.cpp
+++ b/test/diagonal.cpp
@@ -66,6 +66,9 @@ template<typename MatrixType> void diagonal(const MatrixType& m)
     m2.diagonal(N2).coeffRef(0) = Scalar(2)*s1;
     VERIFY_IS_APPROX(m2.diagonal(N2).coeff(0), Scalar(2)*s1);
   }
+
+  VERIFY( m1.diagonal( cols).size()==0 );
+  VERIFY( m1.diagonal(-rows).size()==0 );
 }
 
 template<typename MatrixType> void diagonal_assert(const MatrixType& m) {
@@ -81,6 +84,9 @@ template<typename MatrixType> void diagonal_assert(const MatrixType& m) {
     VERIFY_RAISES_ASSERT( m1.array() *= m1.diagonal().array() );
     VERIFY_RAISES_ASSERT( m1.array() /= m1.diagonal().array() );
   }
+
+  VERIFY_RAISES_ASSERT( m1.diagonal(cols+1) );
+  VERIFY_RAISES_ASSERT( m1.diagonal(-(rows+1)) );
 }
 
 void test_diagonal()
@@ -95,7 +101,6 @@ void test_diagonal()
     CALL_SUBTEST_2( diagonal(MatrixXcd(internal::random<int>(1,EIGEN_TEST_MAX_SIZE), internal::random<int>(1,EIGEN_TEST_MAX_SIZE))) );
     CALL_SUBTEST_1( diagonal(MatrixXf(internal::random<int>(1,EIGEN_TEST_MAX_SIZE), internal::random<int>(1,EIGEN_TEST_MAX_SIZE))) );
     CALL_SUBTEST_1( diagonal(Matrix<float,Dynamic,4>(3, 4)) );
+    CALL_SUBTEST_1( diagonal_assert(MatrixXf(internal::random<int>(1,EIGEN_TEST_MAX_SIZE), internal::random<int>(1,EIGEN_TEST_MAX_SIZE))) );
   }
-
-  CALL_SUBTEST_1( diagonal_assert(MatrixXf(internal::random<int>(1,EIGEN_TEST_MAX_SIZE), internal::random<int>(1,EIGEN_TEST_MAX_SIZE))) );
 }