diff --git a/test/product_threaded.cpp b/test/product_threaded.cpp
index 410f76752..1eb38fbde 100644
--- a/test/product_threaded.cpp
+++ b/test/product_threaded.cpp
@@ -13,9 +13,9 @@
 void test_parallelize_gemm() {
   constexpr int n = 1024;
   constexpr int num_threads = 4;
-  MatrixXf a(n, n);
-  MatrixXf b(n, n);
-  MatrixXf c(n, n);
+  MatrixXf a = MatrixXf::Random(n, n);
+  MatrixXf b = MatrixXf::Random(n, n);
+  MatrixXf c = MatrixXf::Random(n, n);
   c.noalias() = a * b;
 
   ThreadPool pool(num_threads);
diff --git a/unsupported/test/cxx11_tensor_concatenation.cpp b/unsupported/test/cxx11_tensor_concatenation.cpp
index ce78892cb..68455b34d 100644
--- a/unsupported/test/cxx11_tensor_concatenation.cpp
+++ b/unsupported/test/cxx11_tensor_concatenation.cpp
@@ -36,6 +36,8 @@ template <int DataLayout>
 static void test_static_dimension_failure() {
   Tensor<int, 2, DataLayout> left(2, 3);
   Tensor<int, 3, DataLayout> right(2, 3, 1);
+  left.setRandom();
+  right.setRandom();
 
 #ifdef CXX11_TENSOR_CONCATENATION_STATIC_DIMENSION_FAILURE
   // Technically compatible, but we static assert that the inputs have same