diff --git a/state/presence/presence.go b/state/presence/presence.go
index 398ca4ce1cd..a05dda3ece2 100644
--- a/state/presence/presence.go
+++ b/state/presence/presence.go
@@ -696,13 +696,6 @@ func (p *Pinger) prepare() error {
 // sequence in use by the pinger.
 func (p *Pinger) ping() (err error) {
 	logger.Tracef("pinging %q with seq=%d", p.beingKey, p.beingSeq)
-	defer func() {
-		// If the session is killed from underneath us, it panics when we
-		// try to copy it, so deal with that here.
-		if v := recover(); v != nil {
-			err = fmt.Errorf("%v", v)
-		}
-	}()
 	session := p.pings.Database.Session.Copy()
 	defer session.Close()
 	if p.delta == 0 {
diff --git a/state/presence/presence_test.go b/state/presence/presence_test.go
index 70de4f92953..03cc931b916 100644
--- a/state/presence/presence_test.go
+++ b/state/presence/presence_test.go
@@ -111,6 +111,15 @@ func (s *PresenceSuite) TestErrAndDead(c *gc.C) {
 	}
 }
 
+// assertStopped stops a worker and waits until it reports stopped.
+// Use this method in favor of defer w.Stop() because you _must_ ensure
+// that the worker has stopped, and thus is no longer using its mgo
+// session before TearDownTest shuts down the connection.
+func assertStopped(c *gc.C, w worker.Worker) {
+	c.Assert(w.Stop(), gc.IsNil)
+	w.Wait()
+}
+
 func (s *PresenceSuite) TestAliveError(c *gc.C) {
 	w := presence.NewWatcher(s.presence, s.modelTag)
 	c.Assert(w.Stop(), gc.IsNil)
@@ -118,15 +127,16 @@ func (s *PresenceSuite) TestAliveError(c *gc.C) {
 	alive, err := w.Alive("a")
 	c.Assert(err, gc.ErrorMatches, ".*: watcher is dying")
 	c.Assert(alive, jc.IsFalse)
+	w.Wait()
 }
 
 func (s *PresenceSuite) TestWorkflow(c *gc.C) {
 	w := presence.NewWatcher(s.presence, s.modelTag)
 	pa := presence.NewPinger(s.presence, s.modelTag, "a")
 	pb := presence.NewPinger(s.presence, s.modelTag, "b")
-	defer w.Stop()
-	defer pa.Stop()
-	defer pb.Stop()
+	defer assertStopped(c, w)
+	defer assertStopped(c, pa)
+	defer assertStopped(c, pb)
 
 	assertAlive(c, w, "a", false)
 	assertAlive(c, w, "b", false)
@@ -194,7 +204,7 @@ func (s *PresenceSuite) TestWorkflow(c *gc.C) {
 	assertChange(c, cha, presence.Change{"a", false})
 	assertChange(c, chb, presence.Change{"b", false})
 
-	c.Assert(w.Stop(), gc.IsNil)
+	assertStopped(c, w)
 }
 
 func (s *PresenceSuite) TestScale(c *gc.C) {
@@ -220,7 +230,7 @@ func (s *PresenceSuite) TestScale(c *gc.C) {
 
 	c.Logf("Checking who's still alive...")
 	w := presence.NewWatcher(s.presence, s.modelTag)
-	defer w.Stop()
+	defer assertStopped(c, w)
 	w.Sync()
 	ch := make(chan presence.Change)
 	for i := 0; i < N; i++ {
@@ -237,8 +247,8 @@ func (s *PresenceSuite) TestScale(c *gc.C) {
 func (s *PresenceSuite) TestExpiry(c *gc.C) {
 	w := presence.NewWatcher(s.presence, s.modelTag)
 	p := presence.NewPinger(s.presence, s.modelTag, "a")
-	defer w.Stop()
-	defer p.Stop()
+	defer assertStopped(w, c)
+	defer assertStopped(w, p)
 
 	ch := make(chan presence.Change)
 	w.Watch("a", ch)
@@ -270,8 +280,8 @@ func (s *PresenceSuite) TestWatchPeriod(c *gc.C) {
 
 	w := presence.NewWatcher(s.presence, s.modelTag)
 	p := presence.NewPinger(s.presence, s.modelTag, "a")
-	defer w.Stop()
-	defer p.Stop()
+	defer assertStopped(c, w)
+	defer assertStopped(c, p)
 
 	ch := make(chan presence.Change)
 	w.Watch("a", ch)
@@ -315,7 +325,7 @@ func (s *PresenceSuite) TestWatchUnwatchOnQueue(c *gc.C) {
 func (s *PresenceSuite) TestRestartWithoutGaps(c *gc.C) {
 	p := presence.NewPinger(s.presence, s.modelTag, "a")
 	c.Assert(p.Start(), gc.IsNil)
-	defer p.Stop()
+	defer assertStopped(c, p)
 
 	done := make(chan bool)
 	go func() {
@@ -339,7 +349,7 @@ func (s *PresenceSuite) TestRestartWithoutGaps(c *gc.C) {
 			w := presence.NewWatcher(s.presence, s.modelTag)
 			w.Sync()
 			alive, err := w.Alive("a")
-			c.Check(w.Stop(), gc.IsNil)
+			assertStopped(c, w)
 			if !c.Check(err, jc.ErrorIsNil) || !c.Check(alive, jc.IsTrue) {
 				break
 			}
@@ -369,9 +379,9 @@ func (s *PresenceSuite) TestPingerPeriodAndResilience(c *gc.C) {
 	w := presence.NewWatcher(s.presence, s.modelTag)
 	p1 := presence.NewPinger(s.presence, s.modelTag, "a")
 	p2 := presence.NewPinger(s.presence, s.modelTag, "a")
-	defer w.Stop()
-	defer p1.Stop()
-	defer p2.Stop()
+	defer assertStopped(c, w)
+	defer assertStopped(c, p1)
+	defer assertStopped(c, p2)
 
 	// Start p1 and let it go on.
 	c.Assert(p1.Start(), gc.IsNil)
@@ -399,8 +409,8 @@ func (s *PresenceSuite) TestPingerPeriodAndResilience(c *gc.C) {
 func (s *PresenceSuite) TestStartSync(c *gc.C) {
 	w := presence.NewWatcher(s.presence, s.modelTag)
 	p := presence.NewPinger(s.presence, s.modelTag, "a")
-	defer w.Stop()
-	defer p.Stop()
+	defer assertStopped(c, w)
+	defer assertStopped(c, p)
 
 	ch := make(chan presence.Change)
 	w.Watch("a", ch)
@@ -428,8 +438,8 @@ func (s *PresenceSuite) TestStartSync(c *gc.C) {
 func (s *PresenceSuite) TestSync(c *gc.C) {
 	w := presence.NewWatcher(s.presence, s.modelTag)
 	p := presence.NewPinger(s.presence, s.modelTag, "a")
-	defer w.Stop()
-	defer p.Stop()
+	defer assertStopped(c, w)
+	defer assertStopped(c, p)
 
 	ch := make(chan presence.Change)
 	w.Watch("a", ch)
@@ -467,8 +477,8 @@ func (s *PresenceSuite) TestSync(c *gc.C) {
 func (s *PresenceSuite) TestFindAllBeings(c *gc.C) {
 	w := presence.NewWatcher(s.presence, s.modelTag)
 	p := presence.NewPinger(s.presence, s.modelTag, "a")
-	defer w.Stop()
-	defer p.Stop()
+	defer assertStopped(c, w)
+	defer assertStopped(c, p)
 
 	ch := make(chan presence.Change)
 	w.Watch("a", ch)
@@ -493,12 +503,12 @@ func (s *PresenceSuite) TestFindAllBeings(c *gc.C) {
 func (s *PresenceSuite) TestTwoEnvironments(c *gc.C) {
 	key := "a"
 	w1, p1, ch1 := s.setup(c, key)
-	defer w1.Stop()
-	defer p1.Stop()
+	defer assertStopped(c, w1)
+	defer assertStopped(c, p1)
 
 	w2, p2, ch2 := s.setup(c, key)
-	defer w2.Stop()
-	defer p2.Stop()
+	defer assertStopped(c, w2)
+	defer assertStopped(c, p2)
 
 	c.Assert(p1.Start(), gc.IsNil)
 	w1.StartSync()