diff --git a/dotsandboxes.cxx b/dotsandboxes.cxx
index f506330..91d7010 100644
--- a/dotsandboxes.cxx
+++ b/dotsandboxes.cxx
@@ -13,6 +13,7 @@
 #include <iostream>
 #include <sstream>
 #include <cstdio>
+#include <cstring>
 
 #define pt std::cout <<
 #define pter std::cerr <<