diff --git a/src/ca/cac.cpp b/src/ca/cac.cpp
index c4c407e3c..be5c438af 100644
--- a/src/ca/cac.cpp
+++ b/src/ca/cac.cpp
@@ -1782,7 +1782,6 @@ void cac::preemptiveCallbackUnlock ()
         epicsAutoMutex autoMutex ( this->mutex );
         assert ( this->recvThreadsPendingCount > 0 );
         this->recvThreadsPendingCount--;
-        unsigned noThreadsWaiting;
         if ( this->pCallbackLocker ) {
             if ( this->recvThreadsPendingCount == 1u ) {
                 signalRequired = true;
@@ -1791,6 +1790,9 @@ void cac::preemptiveCallbackUnlock ()
                 signalRequired = false;
             }
         }
+        else {
+            signalRequired = false;
+        }
     }
     if ( signalRequired ) {
         this->noRecvThreadsPending.signal ();