diff --git a/src/libCom/osi/epicsThread.h b/src/libCom/osi/epicsThread.h
index 1584ea794..9081b14f2 100644
--- a/src/libCom/osi/epicsThread.h
+++ b/src/libCom/osi/epicsThread.h
@@ -105,7 +105,7 @@ epicsShareFunc void * epicsShareAPI epicsThreadPrivateGet(epicsThreadPrivateId);
 #include "epicsEvent.h"
 
 
-class epicsThreadRunable {
+class epicsShareClass epicsThreadRunable {
 public:
     virtual void run() = 0;
     virtual void stop();