diff --git a/tests/cpp/common/test_categorical.cc b/tests/cpp/common/test_categorical.cc
index 522dfd2af..4e6e696ec 100644
--- a/tests/cpp/common/test_categorical.cc
+++ b/tests/cpp/common/test_categorical.cc
@@ -66,7 +66,8 @@ TEST(Categorical, MinimalSet) {
 
   HostDeviceVector<float> predt;
   {
-    std::vector<float> data{kCat, kCat + 1, 32, 33, 34};
+    std::vector<float> data{static_cast<float>(kCat),
+                            static_cast<float>(kCat + 1), 32.0f, 33.0f, 34.0f};
     auto test = GetDMatrixFromData(data, data.size(), kCols);
     learner->Predict(test, false, &predt, 0, 0, false, /*pred_leaf=*/true);
     ASSERT_EQ(predt.Size(), data.size());