diff --git a/src/SPIN/atom_vec_spin.cpp b/src/SPIN/atom_vec_spin.cpp
index 276bc34e64..8b47eff624 100644
--- a/src/SPIN/atom_vec_spin.cpp
+++ b/src/SPIN/atom_vec_spin.cpp
@@ -23,9 +23,9 @@
    and molecular dynamics. Journal of Computational Physics.
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cmath>
+#include <cstdlib>
+#include <cstring>
 #include "atom.h"
 #include "atom_vec_spin.h"
 #include "comm.h"
diff --git a/src/SPIN/compute_spin.cpp b/src/SPIN/compute_spin.cpp
index b508d0624f..b67f62d53d 100644
--- a/src/SPIN/compute_spin.cpp
+++ b/src/SPIN/compute_spin.cpp
@@ -22,7 +22,7 @@
 ------------------------------------------------------------------------- */
 
 #include <mpi.h>
-#include <string.h>
+#include <cstring>
 #include "atom.h"
 #include "compute_spin.h"
 #include "domain.h"
diff --git a/src/SPIN/fix_langevin_spin.cpp b/src/SPIN/fix_langevin_spin.cpp
index 3650651457..cb34465482 100644
--- a/src/SPIN/fix_langevin_spin.cpp
+++ b/src/SPIN/fix_langevin_spin.cpp
@@ -22,9 +22,9 @@
 ------------------------------------------------------------------------- */
 
 #include <mpi.h>
-#include <math.h>
-#include <string.h>
-#include <stdlib.h>
+#include <cmath>
+#include <cstring>
+#include <cstdlib>
 
 #include "atom.h"
 #include "atom_vec_ellipsoid.h"
diff --git a/src/SPIN/fix_nve_spin.cpp b/src/SPIN/fix_nve_spin.cpp
index 415c2352d4..b75f03212a 100644
--- a/src/SPIN/fix_nve_spin.cpp
+++ b/src/SPIN/fix_nve_spin.cpp
@@ -21,9 +21,9 @@
    and molecular dynamics. Journal of Computational Physics.
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdio.h>
-#include <string.h>
+#include <cmath>
+#include <cstdio>
+#include <cstring>
 
 #include "atom.h"
 #include "atom_vec.h"
diff --git a/src/SPIN/fix_precession_spin.cpp b/src/SPIN/fix_precession_spin.cpp
index bcdd62413d..b908478952 100644
--- a/src/SPIN/fix_precession_spin.cpp
+++ b/src/SPIN/fix_precession_spin.cpp
@@ -21,10 +21,10 @@
    and molecular dynamics. Journal of Computational Physics.
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cmath>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 
 #include "atom.h"
 #include "domain.h"
diff --git a/src/SPIN/pair_spin.cpp b/src/SPIN/pair_spin.cpp
index b6cf07e60c..398206b26e 100644
--- a/src/SPIN/pair_spin.cpp
+++ b/src/SPIN/pair_spin.cpp
@@ -21,9 +21,9 @@
    and molecular dynamics. Journal of Computational Physics.
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cmath>
+#include <cstdlib>
+#include <cstring>
 
 #include "atom.h"
 #include "comm.h"
diff --git a/src/SPIN/pair_spin_dmi.cpp b/src/SPIN/pair_spin_dmi.cpp
index 4ea6cfd0cc..b792969c5d 100644
--- a/src/SPIN/pair_spin_dmi.cpp
+++ b/src/SPIN/pair_spin_dmi.cpp
@@ -21,9 +21,9 @@
    and molecular dynamics. Journal of Computational Physics.
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cmath>
+#include <cstdlib>
+#include <cstring>
 
 #include "atom.h"
 #include "comm.h"
diff --git a/src/SPIN/pair_spin_exchange.cpp b/src/SPIN/pair_spin_exchange.cpp
index cb2d7424cf..1b7b36b6db 100644
--- a/src/SPIN/pair_spin_exchange.cpp
+++ b/src/SPIN/pair_spin_exchange.cpp
@@ -21,9 +21,9 @@
    and molecular dynamics. Journal of Computational Physics.
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cmath>
+#include <cstdlib>
+#include <cstring>
 
 #include "atom.h"
 #include "comm.h"
diff --git a/src/SPIN/pair_spin_magelec.cpp b/src/SPIN/pair_spin_magelec.cpp
index 77bf42159a..315b691d17 100644
--- a/src/SPIN/pair_spin_magelec.cpp
+++ b/src/SPIN/pair_spin_magelec.cpp
@@ -21,9 +21,9 @@
    and molecular dynamics. Journal of Computational Physics.
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cmath>
+#include <cstdlib>
+#include <cstring>
 
 #include "atom.h"
 #include "comm.h"
diff --git a/src/SPIN/pair_spin_neel.cpp b/src/SPIN/pair_spin_neel.cpp
index 05999170eb..0daafad756 100644
--- a/src/SPIN/pair_spin_neel.cpp
+++ b/src/SPIN/pair_spin_neel.cpp
@@ -21,9 +21,9 @@
    and molecular dynamics. Journal of Computational Physics.
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cmath>
+#include <cstdlib>
+#include <cstring>
 
 #include "atom.h"
 #include "comm.h"