diff --git a/gui/webgui6/src/TWebCanvas.cxx b/gui/webgui6/src/TWebCanvas.cxx
index 782ee5a762e4712d30dab3960493e948fda457a6..d85e4016ffb733ec998e89cd88885c8e485e2782 100644
--- a/gui/webgui6/src/TWebCanvas.cxx
+++ b/gui/webgui6/src/TWebCanvas.cxx
@@ -26,6 +26,7 @@
 #include "TList.h"
 #include "TH1.h"
 #include "TEnv.h"
+#include "TError.h"
 #include "TGraph.h"
 #include "TBufferJSON.h"
 #include "Riostream.h"