diff --git a/libweave/src/notification/xmpp_channel.cc b/libweave/src/notification/xmpp_channel.cc
index 542ad61..c7bc35b 100644
--- a/libweave/src/notification/xmpp_channel.cc
+++ b/libweave/src/notification/xmpp_channel.cc
@@ -311,6 +311,7 @@
 }
 
 void XmppChannel::SendMessage(const std::string& message) {
+  CHECK(stream_) << "No XMPP socket stream available";
   if (write_pending_) {
     queued_write_data_ += message;
     return;
@@ -486,6 +487,12 @@
 
 void XmppChannel::PingServer(base::TimeDelta timeout) {
   VLOG(1) << "Sending XMPP ping";
+  if (!IsConnected()) {
+    LOG(WARNING) << "XMPP channel is not connected";
+    Restart();
+    return;
+  }
+
   // Send an XMPP Ping request as defined in XEP-0199 extension:
   // http://xmpp.org/extensions/xep-0199.html
   iq_stanza_handler_->SendRequestWithCustomTimeout(