diff --git a/include/pika_admin.h b/include/pika_admin.h
index 93b9ed29f1..3c38fc01aa 100644
--- a/include/pika_admin.h
+++ b/include/pika_admin.h
@@ -5,6 +5,9 @@
 
 #ifndef PIKA_ADMIN_H_
 #define PIKA_ADMIN_H_
+
+#include <sstream>
+
 #include "include/pika_command.h"
 #include "include/pika_client_conn.h"
 
diff --git a/include/pika_hub_manager.h b/include/pika_hub_manager.h
index bc06d64a06..88e3939d3c 100644
--- a/include/pika_hub_manager.h
+++ b/include/pika_hub_manager.h
@@ -11,6 +11,7 @@
 #include <set>
 #include <memory>
 #include <future>
+#include <sstream>
 
 #include "pink/include/server_thread.h"
 #include "pink/include/pink_thread.h"