diff --git a/src/ca/cacNotify.cpp b/src/ca/cacNotify.cpp
index e4d1ad32e..a89e76421 100644
--- a/src/ca/cacNotify.cpp
+++ b/src/ca/cacNotify.cpp
@@ -44,7 +44,7 @@ void cacNotify::completionNotify ()
 
 void cacNotify::completionNotify ( unsigned type, unsigned long count, const void *pData )
 {
-    ca_printf ("IO completion with no handler installed? type=%u count=%u data pointer=%p\n",
+    ca_printf ("CAC: IO completion with no handler installed? type=%u count=%u data pointer=%p\n",
                 type, count, pData);
 }