diff --git a/cpp/basix/math.h b/cpp/basix/math.h
index 18fe21142..a8e2fdb75 100644
--- a/cpp/basix/math.h
+++ b/cpp/basix/math.h
@@ -310,9 +310,9 @@ template <typename U, typename V, typename W>
 void dot(const U& A, const V& B, W&& C)
 {
   assert(A.extent(1) == B.extent(0));
-  assert(C.extent(0) == C.extent(0));
+  assert(C.extent(0) == A.extent(0));
   assert(C.extent(1) == B.extent(1));
-  if (A.extent(0) * B.extent(1) * A.extent(1) < 4096)
+  if (A.extent(0) * B.extent(1) * A.extent(1) < 512)
   {
     std::fill_n(C.data_handle(), C.extent(0) * C.extent(1), 0);
     for (std::size_t i = 0; i < A.extent(0); ++i)
diff --git a/test/test_create.py b/test/test_create.py
index 9fdb2e744..f4ab0e712 100644
--- a/test/test_create.py
+++ b/test/test_create.py
@@ -82,3 +82,8 @@ def test_create_element(cell, degree, family, variant):
     except RuntimeError as e:
         if len(e.args) == 0 or "dgesv" in e.args[0]:
             raise e
+
+
+def test_create_high_degree_lagrange():
+    basix.create_element(
+        basix.ElementFamily.P, basix.CellType.hexahedron, 7, basix.LagrangeVariant.gll_isaac)