diff --git a/test/product_symm.cpp b/test/product_symm.cpp
index 92a3f4594..4e020fe95 100644
--- a/test/product_symm.cpp
+++ b/test/product_symm.cpp
@@ -50,7 +50,7 @@ template<typename Scalar, int Size, int OtherSize> void symm(int size = Size, in
   typedef Matrix<Scalar, OtherSize, Size> Rhs2;
   enum { order = OtherSize==1 ? 0 : RowMajor };
   typedef Matrix<Scalar, Size, OtherSize,order> Rhs3;
-  typedef MatrixType::Index Index;
+  typedef typename MatrixType::Index Index;
 
   Index rows = size;
   Index cols = size;