diff --git a/mex/sources/dmm/designInternal.cc b/mex/sources/dmm/designInternal.cc
index e47b8fa0f25ba6e1336266d2490ecfde3cabe9f2..6157a239ea00e64a0ace4833fd6a910aac7c4e40 100644
--- a/mex/sources/dmm/designInternal.cc
+++ b/mex/sources/dmm/designInternal.cc
@@ -1,5 +1,6 @@
 #include <dynmex.h>
 #include <algorithm>
+#include <string.h>
 using namespace std;
 
 extern "C"