diff --git a/src/ca/netiiu.cpp b/src/ca/netiiu.cpp
index 3a905fe8d..3781d6048 100644
--- a/src/ca/netiiu.cpp
+++ b/src/ca/netiiu.cpp
@@ -117,7 +117,8 @@ void netiiu::requestRecvProcessPostponedFlush ()
     return;
 }
 
-void netiiu::uninstallChan ( epicsGuard < cacMutex > &, nciu & )
+void netiiu::uninstallChan ( 
+    epicsGuard < callbackMutex > &, epicsGuard < cacMutex > &, nciu & )
 {
     throw cacChannel::notConnected();
 }
diff --git a/src/ca/netiiu.h b/src/ca/netiiu.h
index 20a8fe975..531c27a33 100644
--- a/src/ca/netiiu.h
+++ b/src/ca/netiiu.h
@@ -66,7 +66,8 @@ public:
         ( cacNotify &, epicsGuard < cacMutex > & ) = 0;
     virtual void requestRecvProcessPostponedFlush () = 0;
     virtual osiSockAddr getNetworkAddress () const = 0;
-    virtual void uninstallChan ( epicsGuard < cacMutex > &, nciu & ) = 0;
+    virtual void uninstallChan ( epicsGuard < callbackMutex > &, 
+        epicsGuard < cacMutex > &, nciu & ) = 0;
     virtual double receiveWatchdogDelay () const = 0;
 };
 
diff --git a/src/ca/udpiiu.cpp b/src/ca/udpiiu.cpp
index 425bb4b56..6d00fb621 100644
--- a/src/ca/udpiiu.cpp
+++ b/src/ca/udpiiu.cpp
@@ -1072,6 +1072,7 @@ int udpiiu::printf ( const char *pformat, ... )
 }
 
 void udpiiu::uninstallChan ( 
+    epicsGuard < callbackMutex > &,
     epicsGuard < cacMutex > &, nciu & chan )
 {
     epicsGuard < udpMutex > guard ( this->mutex );
diff --git a/src/ca/udpiiu.h b/src/ca/udpiiu.h
index 82decfaca..f647df4b8 100644
--- a/src/ca/udpiiu.h
+++ b/src/ca/udpiiu.h
@@ -96,7 +96,8 @@ public:
     void beaconAnomalyNotify ( const epicsTime & currentTime );
     int printf ( const char *pformat, ... );
     unsigned channelCount ( epicsGuard < udpMutex > & ) const;
-    void uninstallChan ( epicsGuard < cacMutex > &, nciu & );
+    void uninstallChan ( 
+        epicsGuard < callbackMutex > &, epicsGuard < cacMutex > &, nciu & );
     bool pushDatagramMsg ( const caHdr & hdr, 
         const void * pExt, ca_uint16_t extsize);
     void shutdown ();