diff --git a/R-package/src/Makevars.win b/R-package/src/Makevars.win
index d343b94c5..d06076def 100644
--- a/R-package/src/Makevars.win
+++ b/R-package/src/Makevars.win
@@ -5,7 +5,7 @@ CXX=`Rcmd config CXX`
 TCFLAGS=`Rcmd config CFLAGS` 
 # expose these flags to R CMD SHLIB
 PKG_CPPFLAGS= -DXGBOOST_CUSTOMIZE_ERROR_ -I$(PKGROOT)  $(SHLIB_OPENMP_CFLAGS)
-XGBFLAG= -O3  -DXGBOOST_CUSTOMIZE_ERROR_ -fPIC  $(SHLIB_OPENMP_CFLAGS)
+XGBFLAG= -O3 -DXGBOOST_CUSTOMIZE_ERROR_ -fPIC  $(SHLIB_OPENMP_CFLAGS)
 PKG_LIBS = $(SHLIB_OPENMP_CFLAGS)
 
 ifeq ($(no_omp),1)
diff --git a/src/io/simple_dmatrix-inl.hpp b/src/io/simple_dmatrix-inl.hpp
index 47be8a41a..5c1093540 100644
--- a/src/io/simple_dmatrix-inl.hpp
+++ b/src/io/simple_dmatrix-inl.hpp
@@ -105,7 +105,9 @@ class DMatrixSimple : public DataMatrix {
 
     if (!silent) {
       printf("%lux%lu matrix with %lu entries is loaded from %s\n",
-             info.num_row(), info.num_col(), row_data_.size(), fname);
+             static_cast<unsigned long>(info.num_row()),
+			 static_cast<unsigned long>(info.num_col()),
+			 static_cast<unsigned long>(row_data_.size()), fname);
     }
     fclose(file);
     // try to load in additional file
@@ -155,7 +157,9 @@ class DMatrixSimple : public DataMatrix {
 
     if (!silent) {
       printf("%lux%lu matrix with %lu entries is loaded",
-             info.num_row(), info.num_col(), row_data_.size());
+             static_cast<unsigned long>(info.num_row()),
+			 static_cast<unsigned long>(info.num_col()),
+			 static_cast<unsigned long>(row_data_.size()));
       if (fname != NULL) {
         printf(" from %s\n", fname);
       } else {
@@ -183,9 +187,12 @@ class DMatrixSimple : public DataMatrix {
 
     if (!silent) {
       printf("%lux%lu matrix with %lu entries is saved to %s\n",
-             info.num_row(), info.num_col(), row_data_.size(), fname);
+             static_cast<unsigned long>(info.num_row()),
+			 static_cast<unsigned long>(info.num_col()),
+			 static_cast<unsigned long>(row_data_.size()), fname);
       if (info.group_ptr.size() != 0) {
-        printf("data contains %lu groups\n", info.group_ptr.size()-1);
+        printf("data contains %u groups\n",
+				static_cast<unsigned>(info.group_ptr.size()-1));
       }
     }
   }
diff --git a/src/learner/dmatrix.h b/src/learner/dmatrix.h
index cd897f1d5..542b6f6f5 100644
--- a/src/learner/dmatrix.h
+++ b/src/learner/dmatrix.h
@@ -98,7 +98,8 @@ struct MetaInfo {
       group_ptr.push_back(group_ptr.back()+nline);
     }
     if (!silent) {
-      printf("%lu groups are loaded from %s\n", group_ptr.size()-1, fname);
+      printf("%u groups are loaded from %s\n",
+			  static_cast<unsigned>(group_ptr.size()-1), fname);
     }
     fclose(fi);
     return true;
diff --git a/src/learner/learner-inl.hpp b/src/learner/learner-inl.hpp
index c01e2ec15..8e7bce0a8 100644
--- a/src/learner/learner-inl.hpp
+++ b/src/learner/learner-inl.hpp
@@ -66,10 +66,11 @@ class BoostLearner {
       snprintf(str_temp, sizeof(str_temp), "%u", num_feature);
       this->SetParam("bst:num_feature", str_temp);
     }
-    snprintf(str_temp, sizeof(str_temp), "%lu", buffer_size);
+    snprintf(str_temp, sizeof(str_temp), "%lu",
+			 static_cast<unsigned long>(buffer_size));
     this->SetParam("num_pbuffer", str_temp);
     if (!silent) {
-      printf("buffer_size=%ld\n", buffer_size);
+      printf("buffer_size=%ld\n", static_cast<long>(buffer_size));
     }
   }
   /*!