diff --git a/src/libCom/osi/epicsThread.cpp b/src/libCom/osi/epicsThread.cpp
index e86d52cc6..17f0eb8a7 100644
--- a/src/libCom/osi/epicsThread.cpp
+++ b/src/libCom/osi/epicsThread.cpp
@@ -13,7 +13,7 @@
 #include "epicsThread.h"
 
 void epicsThreadRunable::stop() {};
-void epicsThreadRunable::show(unsigned int) {};
+void epicsThreadRunable::show(unsigned int) const {};
 
 void epicsThreadCallEntryPoint ( void *pPvt )
 {
diff --git a/src/libCom/osi/epicsThread.h b/src/libCom/osi/epicsThread.h
index 8ad9a2b93..d8bbb4221 100644
--- a/src/libCom/osi/epicsThread.h
+++ b/src/libCom/osi/epicsThread.h
@@ -108,7 +108,7 @@ class epicsShareClass epicsThreadRunable {
 public:
     virtual void run() = 0;
     virtual void stop();
-    virtual void show(unsigned int level);
+    virtual void show(unsigned int level) const;
 };
 
 class epicsShareClass epicsThread {