diff --git a/R-package/src/xgboost_R.cpp b/R-package/src/xgboost_R.cpp
index a199c42d9..b887c60ca 100644
--- a/R-package/src/xgboost_R.cpp
+++ b/R-package/src/xgboost_R.cpp
@@ -28,12 +28,13 @@ extern "C" {
   void (*Check)(int exp, const char *fmt, ...) = XGBoostCheck_R;
   void (*Error)(const char *fmt, ...) = error;
 }
+}  // namespace utils
+
 namespace wrapper {
 bool CheckNAN(float v) {
   return ISNAN(v);
 }
-}
-}  // namespace utils
+} // namespace wrapper
 
 namespace random {
 void Seed(unsigned seed) {
diff --git a/src/tree/updater_colmaker-inl.hpp b/src/tree/updater_colmaker-inl.hpp
index 2ad9ea979..7420947e2 100644
--- a/src/tree/updater_colmaker-inl.hpp
+++ b/src/tree/updater_colmaker-inl.hpp
@@ -423,7 +423,7 @@ class ColMaker: public IUpdater {
       #endif
       int poption = param.parallel_option;
       if (poption == 2) {
-        poption = nsize * 2 < nthread ? 1 : 0;
+        poption = static_cast<int>(nsize) * 2 < nthread ? 1 : 0;
       }
       if (poption == 0) {
         #pragma omp parallel for schedule(dynamic, batch_size)