diff --git a/sdrbase/dsp/spectrumvis.h b/sdrbase/dsp/spectrumvis.h
index ad87a50b8..5e6749826 100644
--- a/sdrbase/dsp/spectrumvis.h
+++ b/sdrbase/dsp/spectrumvis.h
@@ -63,7 +63,7 @@ public:
         { }
     };
 
-    class MsgStartStop : public Message {
+    class SDRBASE_API MsgStartStop : public Message {
         MESSAGE_CLASS_DECLARATION
 
     public: