diff --git a/mex/sources/simulate/SparseMatrix.hh b/mex/sources/simulate/SparseMatrix.hh
index ad596bfc39d216f258935c79e974f0cfd0aef394..203df96f5882e3085adc11f788e234d31598bfbe 100644
--- a/mex/sources/simulate/SparseMatrix.hh
+++ b/mex/sources/simulate/SparseMatrix.hh
@@ -22,9 +22,9 @@
 
 #include <fstream>
 #include <stack>
-#include <math.h>
+#include <cmath>
 #include <map>
-#include <time.h>
+#include <ctime>
 #include "Mem_Mngr.hh"
 
 #define NEW_ALLOC
diff --git a/mex/sources/simulate/linbcg.hh b/mex/sources/simulate/linbcg.hh
index c19713185badd8d3a23a65c56ef1496fdee25b4d..b040c403d22a13f877633bffa845d10b668a71e7 100644
--- a/mex/sources/simulate/linbcg.hh
+++ b/mex/sources/simulate/linbcg.hh
@@ -22,12 +22,11 @@
 
 #include <iostream>
 #include <iomanip>
-#include <math.h>
 #include <cmath>
 #include <complex>
 #include <map>
 #include <string>
-#include <time.h>
+#include <ctime>
 #include "mex.h"
 
 using namespace std;
diff --git a/mex/sources/simulate/simulate.hh b/mex/sources/simulate/simulate.hh
index b98cb1e606e1b9688393a2bd3e909f2cc22e0865..928f87cfb758009b4b4f32b6d9957b8a0ed45327 100644
--- a/mex/sources/simulate/simulate.hh
+++ b/mex/sources/simulate/simulate.hh
@@ -23,10 +23,10 @@
 /*#include <stack>
 #include <set>
 #include <vector>
-#include <math.h>
+#include <cmath>
 #include <iostream>
 #include <fstream>*/
-//#include <time.h>
+//#include <ctime>
 //#include <string>
 /*#include <map>
 #include <algorithm>
diff --git a/preprocessor/BlockTriangular.cc b/preprocessor/BlockTriangular.cc
index ffa586b6447ef9377afcb33c662da4b0acdc21c6..f3c403bb271148c57e372eb0ca40448c75b90c29 100644
--- a/preprocessor/BlockTriangular.cc
+++ b/preprocessor/BlockTriangular.cc
@@ -22,10 +22,10 @@
 #include <iostream>
 #include <sstream>
 #include <fstream>
-#include <time.h>
-#include <stdlib.h>
-#include <string.h>
-#include <math.h>
+#include <ctime>
+#include <cstdlib>
+#include <cstring>
+#include <cmath>
 using namespace std;
 //------------------------------------------------------------------------------
 #include "BlockTriangular.hh"
diff --git a/preprocessor/ExprNode.cc b/preprocessor/ExprNode.cc
index f3b36bbe98973e06ef64529c990c4fb7465fd777..4012c9a6bf7b13c1b51305b2f03ccc74ea8dd914 100644
--- a/preprocessor/ExprNode.cc
+++ b/preprocessor/ExprNode.cc
@@ -21,7 +21,7 @@
 #include <iterator>
 #include <algorithm>
 
-#include <math.h>
+#include <cmath>
 
 #include "ExprNode.hh"
 #include "DataTree.hh"
diff --git a/preprocessor/ModelBlocks.cc b/preprocessor/ModelBlocks.cc
index a772883d40252235522b682b898c1e73b00f9709..a5a33494a5539390affa4678b7fca25fb516084d 100644
--- a/preprocessor/ModelBlocks.cc
+++ b/preprocessor/ModelBlocks.cc
@@ -17,8 +17,8 @@
  * along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdlib.h>
-#include <stdio.h>
+#include <cstdlib>
+#include <cstdio>
 #include <iostream>
 #include <sstream>
 #include <fstream>
diff --git a/preprocessor/ModelNormalization.cc b/preprocessor/ModelNormalization.cc
index 11a14f06aeb1363de24627fcf2d05d49ea8771ab..040fdf6dd7b863f27f152c93ba227cebe9164814 100644
--- a/preprocessor/ModelNormalization.cc
+++ b/preprocessor/ModelNormalization.cc
@@ -18,8 +18,8 @@
  */
 
 //#define DEBUG
-#include <stdio.h>
-#include <stdlib.h>
+#include <cstdio>
+#include <cstdlib>
 #include <iostream>
 #include <sstream>
 #include <fstream>
diff --git a/preprocessor/ModelTree.cc b/preprocessor/ModelTree.cc
index 6f2ebf49fba85d9d1ffe70450eb0fa195c9bd09d..b2e7ee74f08dd788b13abf66fb76be3c4d8d1720 100644
--- a/preprocessor/ModelTree.cc
+++ b/preprocessor/ModelTree.cc
@@ -21,7 +21,7 @@
 #include <fstream>
 #include <sstream>
 
-#include <math.h>
+#include <cmath>
 
 #include "ModelTree.hh"
 #include "Interface.hh"
diff --git a/preprocessor/Model_Graph.cc b/preprocessor/Model_Graph.cc
index 4ce54c599af18a28aff47dbf527ebb60785e3395..8103ac9f316f05110e1d144e3564c45f1324b4e3 100644
--- a/preprocessor/Model_Graph.cc
+++ b/preprocessor/Model_Graph.cc
@@ -17,13 +17,13 @@
  * along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdlib.h>
-#include <stdio.h>
+#include <cstdlib>
+#include <cstdio>
 #include <iostream>
 #include <string>
-#include <sys/time.h>
+#include <ctime>
 #include <stack>
-#include <math.h>
+#include <cmath>
 #include "ModelTree.hh"
 #include "Model_Graph.hh"
 #include "BlockTriangular.hh"
diff --git a/preprocessor/SymbolGaussElim.cc b/preprocessor/SymbolGaussElim.cc
index 24a082ccda551bb4bb03ea3aa96d6b1c0e847b0b..2a17fefafc520135e983746bf19a389ac4e19d0c 100644
--- a/preprocessor/SymbolGaussElim.cc
+++ b/preprocessor/SymbolGaussElim.cc
@@ -17,13 +17,13 @@
  * along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdlib.h>
-#include <stdio.h>
+#include <cstdlib>
+#include <cstdio>
 #include <iostream>
 #include <string>
-#include <sys/time.h>
+#include <ctime>
 #include <stack>
-#include <math.h>
+#include <cmath>
 #include <fstream>
 
 #include "ModelTree.hh"