diff --git a/lib/atc/Array.h b/lib/atc/Array.h
index 9df6cbbda245d1bc4730d124a1a6980bbad2dae4..21e66a95512b4b73b2e66e482312d8dd09110d19 100644
--- a/lib/atc/Array.h
+++ b/lib/atc/Array.h
@@ -4,7 +4,7 @@
 #include <cstdlib>
 #include <iostream>
 #include <string>
-#include <stdio.h>
+#include <cstdio>
 
 // for macros
 #include "MatrixDef.h"
diff --git a/lib/atc/Array2D.h b/lib/atc/Array2D.h
index 8d3af47e12c14bea9e852928fea9b9cdee180009..25f895f72ccbaa82323ca1617d66f2fe8d519aba 100644
--- a/lib/atc/Array2D.h
+++ b/lib/atc/Array2D.h
@@ -2,10 +2,9 @@
 #define ARRAY2D_H
 
 #include <cstdlib>
+#include <cstdio>
 #include <string>
 #include <iostream>
-#include <cstdlib>
-#include <stdio.h>
 
 #include "Array.h"
 
diff --git a/lib/atc/ElectronPhononExchange.cpp b/lib/atc/ElectronPhononExchange.cpp
index 2ed25fc557dd8494a9556a4fe86fa199fbc34d41..0ccc8ec67e1c70df9ff298eb0ee5b13b83afc006 100644
--- a/lib/atc/ElectronPhononExchange.cpp
+++ b/lib/atc/ElectronPhononExchange.cpp
@@ -5,7 +5,7 @@
 
 #include <iostream>
 #include <vector>
-#include <math.h>
+#include <cmath>
 
 using ATC_Utility::command_line;
 using ATC_Utility::str2dbl;
diff --git a/lib/atc/FE_Element.cpp b/lib/atc/FE_Element.cpp
index cfc59aa601d8b8019d5efdff63ffa3a6abc24a81..9eec08c483e971a4574c41ea653856a776841b41 100644
--- a/lib/atc/FE_Element.cpp
+++ b/lib/atc/FE_Element.cpp
@@ -8,7 +8,7 @@
 #include "Utility.h"
 
 // Other headers
-#include "math.h"
+#include <cmath>
 
 using ATC_Utility::dbl_geq;
 using ATC_Utility::det3;
diff --git a/lib/atc/FE_Engine.cpp b/lib/atc/FE_Engine.cpp
index 0e94dfa0318387d27c5fffa9f3f717553075eb2b..efcde66d782fa9ce27bd596ad3418645c6b30b2f 100644
--- a/lib/atc/FE_Engine.cpp
+++ b/lib/atc/FE_Engine.cpp
@@ -7,8 +7,8 @@
 #include "KernelFunction.h"
 #include "Utility.h"
 #include "MPI_Wrappers.h"
-#include <stdio.h>
-#include <stdlib.h>
+#include <cstdio>
+#include <cstdlib>
 #include <map>
 #include <string>
 
diff --git a/lib/atc/FE_Interpolate.cpp b/lib/atc/FE_Interpolate.cpp
index 3f41e3002994db342561e2a5b8f2a6f5112ee9ec..19753a80079a6fe7e4e69d1cc624ef55c2ab56cb 100644
--- a/lib/atc/FE_Interpolate.cpp
+++ b/lib/atc/FE_Interpolate.cpp
@@ -5,7 +5,7 @@
 #include "FE_Quadrature.h"
 
 // Other headers
-#include "math.h"
+#include <cmath>
 
 using std::map;
 using std::vector;
diff --git a/lib/atc/FE_Mesh.cpp b/lib/atc/FE_Mesh.cpp
index 6225a1b192af060bdbccecd5d59ddd014414b1e8..b090bf2881bdbb9855c7098ccc7b5f2a6d4a4f7a 100644
--- a/lib/atc/FE_Mesh.cpp
+++ b/lib/atc/FE_Mesh.cpp
@@ -6,7 +6,7 @@
 #include "OutputManager.h"
 #include "Utility.h"
 #include <sstream>
-#include <assert.h>
+#include <cassert>
 #include <algorithm>
 #include <cmath>
 #include <functional>
diff --git a/lib/atc/FE_Mesh.h b/lib/atc/FE_Mesh.h
index b37cb1e8bad05ef6639e8aa83cb4b83327b844b7..be40d7cb28e21265646d5320a2ecce105eddb98c 100644
--- a/lib/atc/FE_Mesh.h
+++ b/lib/atc/FE_Mesh.h
@@ -12,7 +12,7 @@
 #include <map>
 #include <set>
 #include <utility>
-#include <float.h>
+#include <cfloat>
 #include <string>
 #include <vector>
 #include "mpi.h"
diff --git a/lib/atc/Function.h b/lib/atc/Function.h
index 7368589e96ef65a958ce445040c3b92eaccd95e8..4572009f92a39729fb4b5342aaeb691b8099a76d 100644
--- a/lib/atc/Function.h
+++ b/lib/atc/Function.h
@@ -1,7 +1,7 @@
 #ifndef XT_FUNCTION_H
 #define XT_FUNCTION_H
 
-#include <math.h>
+#include <cmath>
 #include <string>
 #include <set>
 #include <cstdlib>
diff --git a/lib/atc/GMRES.h b/lib/atc/GMRES.h
index 0cffe9837f952b59f0f29f260107b90e6739267c..a64fc70c009bfa5cd51766ca67c1dbe32bc5be75 100644
--- a/lib/atc/GMRES.h
+++ b/lib/atc/GMRES.h
@@ -19,7 +19,7 @@
 //  
 //*****************************************************************
 
-#include <math.h>
+#include <cmath>
 
 
 template<class Real>
diff --git a/lib/atc/KD_Tree.cpp b/lib/atc/KD_Tree.cpp
index 362bd70d34bd35f8d94d18d7c52e36978dab0f03..1432663e8064b60b8862e707d99aa010fb0245c1 100644
--- a/lib/atc/KD_Tree.cpp
+++ b/lib/atc/KD_Tree.cpp
@@ -1,5 +1,5 @@
 #include "KD_Tree.h"
-#include <assert.h>
+#include <cassert>
 
 using std::vector;
 
diff --git a/lib/atc/KD_Tree.h b/lib/atc/KD_Tree.h
index 6c788c407112948bbcbbed4f3c8d2f612728fa69..3877cd40993bd910744b19b94b898842431af1b2 100644
--- a/lib/atc/KD_Tree.h
+++ b/lib/atc/KD_Tree.h
@@ -4,7 +4,7 @@
 #include "Array2D.h"
 #include "MatrixDef.h"
 #include "MatrixLibrary.h"
-#include <math.h>
+#include <cmath>
 #include <vector>
 #include <utility>
 
diff --git a/lib/atc/KernelFunction.cpp b/lib/atc/KernelFunction.cpp
index 91f99a61494f185145af66f0d709dc209af7e6e0..80e41a15509bd1c4efd77f42e5d55e30e0a6f910 100644
--- a/lib/atc/KernelFunction.cpp
+++ b/lib/atc/KernelFunction.cpp
@@ -1,5 +1,5 @@
 #include "KernelFunction.h"
-#include "math.h"
+#include <cmath>
 #include <vector>
 #include "ATC_Error.h"
 #include "Quadrature.h"
diff --git a/lib/atc/LammpsInterface.h b/lib/atc/LammpsInterface.h
index 2c7826952218d27109be56e1dbef6aaae764376a..2032571da5df99e642da3b761eb1464c176ed098 100644
--- a/lib/atc/LammpsInterface.h
+++ b/lib/atc/LammpsInterface.h
@@ -2,7 +2,7 @@
 #define LAMMPS_INTERFACE_H
 
 #include <iostream>
-#include <stdlib.h>
+#include <cstdlib>
 #include <map>
 #include <iostream>
 #include <string>
diff --git a/lib/atc/OutputManager.cpp b/lib/atc/OutputManager.cpp
index 414c5173e7b7cfb1bde38a5a263480eccec264d5..4340c8b8b0a3ca3c308be3838385a2b36a7b3c9a 100644
--- a/lib/atc/OutputManager.cpp
+++ b/lib/atc/OutputManager.cpp
@@ -1,6 +1,6 @@
 #include <string>
 #include <fstream>
-#include <stdio.h>
+#include <cstdio>
 #include <sstream>
 #include "OutputManager.h"
 #include "ATC_Error.h"
diff --git a/lib/atc/ShapeFunction.h b/lib/atc/ShapeFunction.h
index 724e66924feadf790deaf17bbda8b64e84edb44a..62b2138cd7fd7b994d7aaa5d7c071ec21c27966e 100644
--- a/lib/atc/ShapeFunction.h
+++ b/lib/atc/ShapeFunction.h
@@ -5,10 +5,10 @@
 
 #include "DependencyManager.h"
 #include "PaqAtcUtility.h"
-#include <map.h>
-#include <vector.h>
-#include <set.h>
-#include <pair.h>
+#include <map>
+#include <vector>
+#include <set>
+#include <pair>
 
 namespace ATC {
 
diff --git a/lib/atc/Utility.h b/lib/atc/Utility.h
index f9e99ff194fb8245618c791858cd308208876a1d..d975d4804ae87ac5ee9043ae206bedbf1e815782 100644
--- a/lib/atc/Utility.h
+++ b/lib/atc/Utility.h
@@ -13,7 +13,7 @@
 #include <sstream>
 #include <iomanip>
 #include <algorithm>
-#include "math.h"
+#include <cmath>
 
 #include "ATC_Error.h"