diff --git a/test/block.cpp b/test/block.cpp
index c21ce29ca..1c2e080ad 100644
--- a/test/block.cpp
+++ b/test/block.cpp
@@ -159,7 +159,7 @@ template<typename MatrixType> void block(const MatrixType& m)
 template<typename MatrixType>
 void compare_using_data_and_stride(const MatrixType& m)
 {
-  typedef MatrixType::Index Index;
+  typedef typename MatrixType::Index Index;
   Index rows = m.rows();
   Index cols = m.cols();
   Index size = m.size();