diff --git a/xroot_plugins/XrdSsiCtaRequestMessage.cpp b/xroot_plugins/XrdSsiCtaRequestMessage.cpp
index 5ed7a836baa8e54fe8907454f6823cd9a710e95b..ea2c554418201b49c21bf1493c1d74e7990c8fc9 100644
--- a/xroot_plugins/XrdSsiCtaRequestMessage.cpp
+++ b/xroot_plugins/XrdSsiCtaRequestMessage.cpp
@@ -44,6 +44,7 @@ using XrdSsiPb::PbException;
 
 #include <limits>
 #include <sstream>
+#include <string>
 
 namespace cta {
 namespace xrd {