diff --git a/R-package/src/xgboost_R.cpp b/R-package/src/xgboost_R.cpp
index 39e6a1b66..a199c42d9 100644
--- a/R-package/src/xgboost_R.cpp
+++ b/R-package/src/xgboost_R.cpp
@@ -28,6 +28,11 @@ extern "C" {
   void (*Check)(int exp, const char *fmt, ...) = XGBoostCheck_R;
   void (*Error)(const char *fmt, ...) = error;
 }
+namespace wrapper {
+bool CheckNAN(float v) {
+  return ISNAN(v);
+}
+}
 }  // namespace utils
 
 namespace random {
diff --git a/wrapper/xgboost_wrapper.cpp b/wrapper/xgboost_wrapper.cpp
index 659ee05ed..67c6c41d5 100644
--- a/wrapper/xgboost_wrapper.cpp
+++ b/wrapper/xgboost_wrapper.cpp
@@ -5,6 +5,7 @@
 #include <vector>
 #include <string>
 #include <cstring>
+#include <cmath>
 #include <algorithm>
 // include all std functions
 using namespace std;
@@ -96,19 +97,19 @@ class Booster: public learner::BoostLearner {
  private:
   bool init_model;
 };
+#if !defined(XGBOOST_STRICT_CXX98_)
+inline bool CheckNAN(float v) {
+  return isnan(v);
+}
+#else
+// redirect to defs in R
+bool CheckNAN(float v);
+#endif
 }  // namespace wrapper
 }  // namespace xgboost
 
 using namespace xgboost::wrapper;
 
-inline bool checknan(float v) {
-#if defined(__SUN__) || defined(__sum__) || defined(__SunOS)
-  return !(v==v);
-#else
-  return isnan(v);
-#endif
-}
-
 extern "C"{
   void* XGDMatrixCreateFromFile(const char *fname, int silent) {
     return LoadDataMatrix(fname, silent != 0, false);
@@ -162,7 +163,7 @@ extern "C"{
                                bst_ulong nrow,
                                bst_ulong ncol,
                                float  missing) {    
-    bool nan_missing = checknan(missing);
+    bool nan_missing = CheckNAN(missing);
     DMatrixSimple *p_mat = new DMatrixSimple();
     DMatrixSimple &mat = *p_mat;
     mat.info.info.num_row = nrow;
@@ -170,7 +171,7 @@ extern "C"{
     for (bst_ulong i = 0; i < nrow; ++i, data += ncol) {
       bst_ulong nelem = 0;
       for (bst_ulong j = 0; j < ncol; ++j) {
-        if (checknan(data[j])) {
+        if (CheckNAN(data[j])) {
           utils::Check(nan_missing,
                        "There are NAN in the matrix, however, you did not set missing=NAN"); 
         } else {