diff --git a/RootCnv/src/RootPerfMonSvc.cpp b/RootCnv/src/RootPerfMonSvc.cpp
index 99d0ac3d28aa6446314890d9f98acc8aa28175e1..66de61aa2cc4fb2d756c96050e95f4705aa25bca 100644
--- a/RootCnv/src/RootPerfMonSvc.cpp
+++ b/RootCnv/src/RootPerfMonSvc.cpp
@@ -30,6 +30,7 @@
 #include "TBranch.h"
 #include "TDirectory.h"
 #include "TMap.h"
+#include "TObjString.h"
 #include "TSystem.h"
 
 using namespace std;