diff --git a/Net/include/Poco/Net/HTTPNTLMCredentials.h b/Net/include/Poco/Net/HTTPNTLMCredentials.h
index 1dea0f17c..48206d87e 100644
--- a/Net/include/Poco/Net/HTTPNTLMCredentials.h
+++ b/Net/include/Poco/Net/HTTPNTLMCredentials.h
@@ -19,6 +19,7 @@
 
 
 #include "Poco/Net/Net.h"
+#include <vector>
 
 
 namespace Poco {