diff --git a/CryptClass/AbstractSKA.hpp b/CryptClass/AbstractSKA.hpp
index cb7b27b..57a4a23 100644
--- a/CryptClass/AbstractSKA.hpp
+++ b/CryptClass/AbstractSKA.hpp
@@ -8,6 +8,7 @@
  *
  */
 
+#include <string>
 
 
 /**