diff --git a/NPLib/Core/NPDetectorManager.cxx b/NPLib/Core/NPDetectorManager.cxx
index 4a0e1f0476ee3455ab164b7c4c83f1a9f3988861..4be5e0e1739d822d6eda413371f4850b48fd172f 100644
--- a/NPLib/Core/NPDetectorManager.cxx
+++ b/NPLib/Core/NPDetectorManager.cxx
@@ -26,7 +26,7 @@
 #include <sstream>
 #include <fstream>
 #include <cstdlib>
-
+#include <set>
 // NPL
 #include "NPDetectorFactory.h"
 #include "RootInput.h"