diff --git a/dlls/oleaut32/tmarshal.c b/dlls/oleaut32/tmarshal.c
index e29a7ae0df8..026390f6120 100644
--- a/dlls/oleaut32/tmarshal.c
+++ b/dlls/oleaut32/tmarshal.c
@@ -1185,6 +1185,13 @@ xCall(LPVOID retptr, int method, TMProxyImpl *tpinfo /*, args */)
 	return E_FAIL;
     }
 
+    if (!tpinfo->chanbuf)
+    {
+        WARN("Tried to use disconnected proxy\n");
+        LeaveCriticalSection(&tpinfo->crit);
+        return RPC_E_DISCONNECTED;
+    }
+
     if (relaydeb) {
        TRACE_(olerelay)("->");
 	if (iname)
diff --git a/dlls/rpcrt4/ndr_midl.c b/dlls/rpcrt4/ndr_midl.c
index a1822f543d5..1aa6aae7d3b 100644
--- a/dlls/rpcrt4/ndr_midl.c
+++ b/dlls/rpcrt4/ndr_midl.c
@@ -100,6 +100,13 @@ void WINAPI NdrProxySendReceive(void *This,
   HRESULT hr;
 
   TRACE("(%p,%p)\n", This, pStubMsg);
+
+  if (!pStubMsg->pRpcChannelBuffer)
+  {
+    WARN("Trying to use disconnected proxy %p\n", This);
+    RpcRaiseException(RPC_E_DISCONNECTED);
+  }
+
   pStubMsg->dwStubPhase = PROXY_SENDRECEIVE;
   hr = IRpcChannelBuffer_SendReceive(pStubMsg->pRpcChannelBuffer,
                                     (RPCOLEMESSAGE*)pStubMsg->RpcMsg,