diff --git a/Eigen/src/Core/products/GeneralBlockPanelKernel.h b/Eigen/src/Core/products/GeneralBlockPanelKernel.h
index 0890bc690..eb095966b 100644
--- a/Eigen/src/Core/products/GeneralBlockPanelKernel.h
+++ b/Eigen/src/Core/products/GeneralBlockPanelKernel.h
@@ -88,15 +88,15 @@ void computeProductBlockingSizes(Index& k, Index& m, Index& n, Index num_threads
 #ifdef EIGEN_TEST_SPECIFIC_BLOCKING_SIZES
   EIGEN_UNUSED_VARIABLE(num_threads);
   enum {
-    kr = 16,
+    kr = 8,
     mr = Traits::mr,
     nr = Traits::nr
   };
   k = std::min<Index>(k, EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_K);
   if (k > kr) k -= k % kr;
-  m = std::min<Index>(n, EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_M);
+  m = std::min<Index>(m, EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_M);
   if (m > mr) m -= m % mr;
-  n = std::min<Index>(k, EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_N);
+  n = std::min<Index>(n, EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_N);
   if (n > nr) n -= n % nr;
   return;
 #endif