diff --git a/src/laybasic/laybasic/layQtTools.h b/src/laybasic/laybasic/layQtTools.h
index 36a02b368..763a8c706 100644
--- a/src/laybasic/laybasic/layQtTools.h
+++ b/src/laybasic/laybasic/layQtTools.h
@@ -86,7 +86,7 @@ LAYBASIC_PUBLIC void indicate_error (QWidget *le, bool error);
 
 //  Provide missing QSignalBlocker for Qt4
 
-class SignalBlocker
+class LAYBASIC_PUBLIC SignalBlocker
 {
 public:
   SignalBlocker (QWidget *w);