diff --git a/ImageHelper.hh b/ImageHelper.hh
index 782a80a..ebfbf37 100644
--- a/ImageHelper.hh
+++ b/ImageHelper.hh
@@ -26,6 +26,8 @@
 #ifndef ImageHelper_h 
 #define ImageHelper_h 1
 
+#include <string.h>
+#include <stdlib.h>
 #include <stdio.h>
 #include <iostream>
 
diff --git a/evg-thin.cc b/evg-thin.cc
index e0a8a02..3217b2f 100644
--- a/evg-thin.cc
+++ b/evg-thin.cc
@@ -22,6 +22,8 @@
 
 *********************************************************************/
 
+#include <string.h>
+#include <stdlib.h>
 #include "evg-thin.hh"
 #include "utils.hh"
 #include <iostream>
diff --git a/test.cc b/test.cc
index 7282a67..9f633e7 100644
--- a/test.cc
+++ b/test.cc
@@ -23,6 +23,8 @@
 *********************************************************************/
 
 
+#include <string.h>
+#include <stdlib.h>
 #include <iostream>
 #include <float.h>
 #include <math.h>