diff --git a/src/USER-PLUMED/fix_plumed.cpp b/src/USER-PLUMED/fix_plumed.cpp
index 794ab50f82..1b05477e38 100644
--- a/src/USER-PLUMED/fix_plumed.cpp
+++ b/src/USER-PLUMED/fix_plumed.cpp
@@ -1,6 +1,8 @@
-#include "math.h"
-#include "stdlib.h"
-#include "string.h"
+
+#include <cmath>
+#include <cstdlib>
+#include <cstring>
+
 #include "atom.h"
 #include "update.h"
 #include "force.h"