diff --git a/node/src/main/kotlin/net/corda/node/services/messaging/RPCServer.kt b/node/src/main/kotlin/net/corda/node/services/messaging/RPCServer.kt
index e70f80d39d..d3717de4ec 100644
--- a/node/src/main/kotlin/net/corda/node/services/messaging/RPCServer.kt
+++ b/node/src/main/kotlin/net/corda/node/services/messaging/RPCServer.kt
@@ -525,6 +525,7 @@ object RpcServerObservableSerializer : Serializer<Observable<*>>() {
                             }
 
                             override fun onCompleted() {
+                                observableContext.clientAddressToObservables.remove(observableContext.clientAddress, observableId)
                             }
                         }
                 )