diff --git a/p2p/pex_reactor.go b/p2p/pex_reactor.go
index fe55687e0..6e49f6d06 100644
--- a/p2p/pex_reactor.go
+++ b/p2p/pex_reactor.go
@@ -70,7 +70,7 @@ func (r *PEXReactor) OnStart() error {
 		return err
 	}
 	err := r.book.Start()
-	if err != nil {
+	if err != nil && err != cmn.ErrAlreadyStarted {
 		return err
 	}
 	go r.ensurePeersRoutine()
diff --git a/p2p/pex_reactor_test.go b/p2p/pex_reactor_test.go
index 7e97f78cc..e80840b17 100644
--- a/p2p/pex_reactor_test.go
+++ b/p2p/pex_reactor_test.go
@@ -62,13 +62,11 @@ func TestPEXReactorAddRemovePeer(t *testing.T) {
 }
 
 func TestPEXReactorRunning(t *testing.T) {
-	require := require.New(t)
-
 	N := 3
 	switches := make([]*Switch, N)
 
 	dir, err := ioutil.TempDir("", "pex_reactor")
-	require.Nil(err)
+	require.Nil(t, err)
 	defer os.RemoveAll(dir) // nolint: errcheck
 	book := NewAddrBook(dir+"addrbook.json", false)
 	book.SetLogger(log.TestingLogger())
@@ -96,7 +94,7 @@ func TestPEXReactorRunning(t *testing.T) {
 	// start switches
 	for _, s := range switches {
 		err := s.Start() // start switch and reactors
-		require.Nil(err)
+		require.Nil(t, err)
 	}
 
 	assertSomePeersWithTimeout(t, switches, 10*time.Millisecond, 10*time.Second)
diff --git a/p2p/switch.go b/p2p/switch.go
index b72453a50..f41b82959 100644
--- a/p2p/switch.go
+++ b/p2p/switch.go
@@ -1,12 +1,13 @@
 package p2p
 
 import (
-	"errors"
 	"fmt"
 	"math/rand"
 	"net"
 	"time"
 
+	"github.com/pkg/errors"
+
 	crypto "github.com/tendermint/go-crypto"
 	cfg "github.com/tendermint/tendermint/config"
 	cmn "github.com/tendermint/tmlibs/common"
@@ -174,17 +175,13 @@ func (sw *Switch) SetNodePrivKey(nodePrivKey crypto.PrivKeyEd25519) {
 
 // OnStart implements BaseService. It starts all the reactors, peers, and listeners.
 func (sw *Switch) OnStart() error {
-	if err := sw.BaseService.OnStart(); err != nil {
-		return err
-	}
 	// Start reactors
 	for _, reactor := range sw.reactors {
 		err := reactor.Start()
 		if err != nil {
-			return err
+			return errors.Wrapf(err, "failed to start %v", reactor)
 		}
 	}
-
 	// Start listeners
 	for _, listener := range sw.listeners {
 		go sw.listenerRoutine(listener)
@@ -194,7 +191,6 @@ func (sw *Switch) OnStart() error {
 
 // OnStop implements BaseService. It stops all listeners, peers, and reactors.
 func (sw *Switch) OnStop() {
-	sw.BaseService.OnStop()
 	// Stop listeners
 	for _, listener := range sw.listeners {
 		listener.Stop()