diff --git a/Eigen/src/Core/DiagonalMatrix.h b/Eigen/src/Core/DiagonalMatrix.h
index 0c0525028..630c172ed 100644
--- a/Eigen/src/Core/DiagonalMatrix.h
+++ b/Eigen/src/Core/DiagonalMatrix.h
@@ -174,7 +174,7 @@ class DiagonalMatrix
       */
     DiagonalMatrix& operator=(const DiagonalMatrix& other)
     {
-      m_diagonal = other.m_diagonal();
+      m_diagonal = other.diagonal();
       return *this;
     }
     #endif