1 files changed, 1 insertions, 0 deletions
diff --git a/phpcpp.h b/phpcpp.h
index ce1beb5..4e9735d 100644
--- a/phpcpp.h
+++ b/phpcpp.h
@@ -21,6 +21,7 @@
 #include <list>
 #include <exception>
 #include <map>
+#include <set>
 
 /**
  *  Include all headers files that are related to this library