diff --git a/api/machines_test.go b/api/machines_test.go
index a2938ce02..349cda87c 100644
--- a/api/machines_test.go
+++ b/api/machines_test.go
@@ -77,7 +77,7 @@ func TestMachinesListBadNextPageToken(t *testing.T) {
 
 	err = assertErrorResponse(rw, http.StatusBadRequest)
 	if err != nil {
-		t.Error(err.Error())
+		t.Error(err)
 	}
 }
 
diff --git a/api/state_test.go b/api/state_test.go
index 418e08dbf..4107c31b1 100644
--- a/api/state_test.go
+++ b/api/state_test.go
@@ -189,7 +189,7 @@ func TestUnitStateListBadNextPageToken(t *testing.T) {
 
 	err = assertErrorResponse(rw, http.StatusBadRequest)
 	if err != nil {
-		t.Error(err.Error())
+		t.Error(err)
 	}
 }
 
diff --git a/api/units_test.go b/api/units_test.go
index 308d9bc75..ca065cbf2 100644
--- a/api/units_test.go
+++ b/api/units_test.go
@@ -114,7 +114,7 @@ func TestUnitsListBadNextPageToken(t *testing.T) {
 
 	err = assertErrorResponse(rw, http.StatusBadRequest)
 	if err != nil {
-		t.Error(err.Error())
+		t.Error(err)
 	}
 }
 
diff --git a/engine/rpcengine.go b/engine/rpcengine.go
index 93e574eda..2e8504578 100644
--- a/engine/rpcengine.go
+++ b/engine/rpcengine.go
@@ -1,4 +1,4 @@
-// Copyright 2014 CoreOS, Inc.
+// Copyright 2016 The fleet Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -16,9 +16,10 @@ package engine
 
 import (
 	"errors"
-	"strings"
 	"time"
 
+	etcdErr "github.com/coreos/etcd/error"
+
 	"github.com/coreos/fleet/log"
 	"github.com/coreos/fleet/machine"
 	"github.com/coreos/fleet/pkg/lease"
@@ -145,22 +146,23 @@ func rpcAcquireLeadership(reg registry.Registry, lManager lease.Manager, machID
 
 func rpcRenewLeadership(lManager lease.Manager, l lease.Lease, ver int, ttl time.Duration) lease.Lease {
 	err := l.Renew(ttl)
-	if err != nil && strings.Contains(err.Error(), "Key not found") {
-		log.Errorf("Retry renew etcd operation that failed due to %v", err)
-		l, err = lManager.AcquireLease(engineLeaseName, l.MachineID(), ver, ttl)
-		if err != nil {
-			log.Errorf("Engine leadership re-acquisition failed: %v", err)
-			return nil
-		} else if l == nil {
-			log.Infof("Unable to re-acquire engine leadership")
+	if err != nil {
+		if eerr, ok := err.(*etcdErr.Error); ok && eerr.ErrorCode == etcdErr.EcodeKeyNotFound {
+			log.Errorf("Retry renew etcd operation that failed due to %v", err)
+			l, err = lManager.AcquireLease(engineLeaseName, l.MachineID(), ver, ttl)
+			if err != nil {
+				log.Errorf("Engine leadership re-acquisition failed: %v", err)
+				return nil
+			} else if l == nil {
+				log.Infof("Unable to re-acquire engine leadership")
+				return nil
+			}
+			log.Infof("Engine leadership re-acquired")
+			return l
+		} else {
+			log.Errorf("Engine leadership lost, renewal failed: %v", err)
 			return nil
 		}
-		log.Infof("Engine leadership re-acquired")
-		return l
-
-	} else if err != nil {
-		log.Errorf("Engine leadership lost, renewal failed: %v", err)
-		return nil
 	}
 
 	log.Debugf("Engine leadership renewed")
diff --git a/fleetd/fleetd.go b/fleetd/fleetd.go
index 59dddefcb..849c1d4de 100644
--- a/fleetd/fleetd.go
+++ b/fleetd/fleetd.go
@@ -100,13 +100,13 @@ func main() {
 	globalconf.Register("", cfgset)
 	cfg, err := getConfig(cfgset, *cfgPath)
 	if err != nil {
-		log.Fatalf(err.Error())
+		log.Fatal(err)
 	}
 
 	log.Debugf("Creating Server")
 	srv, err := server.New(*cfg, nil)
 	if err != nil {
-		log.Fatalf("Failed creating Server: %v", err.Error())
+		log.Fatalf("Failed creating Server: %v", err)
 	}
 	srv.Run()
 
@@ -120,7 +120,7 @@ func main() {
 
 		cfg, err := getConfig(cfgset, *cfgPath)
 		if err != nil {
-			log.Fatalf(err.Error())
+			log.Fatal(err)
 		}
 
 		log.Infof("Restarting server components")
@@ -135,7 +135,7 @@ func main() {
 		// The new server takes the original listeners.
 		srv, err = server.New(*cfg, oldListeners)
 		if err != nil {
-			log.Fatalf(err.Error())
+			log.Fatal(err)
 		}
 
 		srv.Run()
diff --git a/functional/systemd_test.go b/functional/systemd_test.go
index 408543bee..d1a37448e 100644
--- a/functional/systemd_test.go
+++ b/functional/systemd_test.go
@@ -75,22 +75,22 @@ ExecStart=/usr/bin/sleep 3000
 
 	err = waitForUnitState(mgr, name, unit.UnitState{"loaded", "inactive", "dead", "", hash, ""})
 	if err != nil {
-		t.Error(err.Error())
+		t.Error(err)
 	}
 
 	err = mgr.TriggerStart(name)
 	if err != nil {
-		t.Error(err.Error())
+		t.Error(err)
 	}
 
 	err = waitForUnitState(mgr, name, unit.UnitState{"loaded", "active", "running", "", hash, ""})
 	if err != nil {
-		t.Error(err.Error())
+		t.Error(err)
 	}
 
 	err = mgr.TriggerStop(name)
 	if err != nil {
-		t.Error(err.Error())
+		t.Error(err)
 	}
 
 	mgr.Unload(name)
diff --git a/glide.lock b/glide.lock
index 9fc1dec1f..bfcd8ec1a 100644
--- a/glide.lock
+++ b/glide.lock
@@ -9,6 +9,7 @@ imports:
   version: 488ae52a5190fbf24539e281f13b461b1ac35df4
   subpackages:
   - client
+  - error
   - pkg/pathutil
   - pkg/types
 - name: github.com/coreos/go-semver
diff --git a/glide.yaml b/glide.yaml
index 0dbd241c4..ba4ba2f9c 100644
--- a/glide.yaml
+++ b/glide.yaml
@@ -3,6 +3,7 @@ import:
 - package: github.com/coreos/etcd
   subpackages:
   - client
+  - error
 - package: github.com/coreos/go-semver
   subpackages:
   - semver
diff --git a/pkg/filesystem_test.go b/pkg/filesystem_test.go
index b259508c7..0da1a336f 100644
--- a/pkg/filesystem_test.go
+++ b/pkg/filesystem_test.go
@@ -25,7 +25,7 @@ import (
 func TestListDirectory(t *testing.T) {
 	dir, err := ioutil.TempDir("", "fleet-testing-")
 	if err != nil {
-		t.Fatal(err.Error())
+		t.Fatal(err)
 	}
 
 	defer os.RemoveAll(dir)
@@ -33,7 +33,7 @@ func TestListDirectory(t *testing.T) {
 	for _, name := range []string{"ping", "pong", "foo", "bar", "baz"} {
 		err := ioutil.WriteFile(path.Join(dir, name), []byte{}, 0400)
 		if err != nil {
-			t.Fatal(err.Error())
+			t.Fatal(err)
 		}
 	}
 
@@ -43,7 +43,7 @@ func TestListDirectory(t *testing.T) {
 
 	got, err := ListDirectory(dir, filterFunc)
 	if err != nil {
-		t.Fatal(err.Error())
+		t.Fatal(err)
 	}
 
 	want := []string{"baz", "ping", "pong"}
diff --git a/systemd/manager_test.go b/systemd/manager_test.go
index 9e73ad49c..e9a7650cc 100644
--- a/systemd/manager_test.go
+++ b/systemd/manager_test.go
@@ -25,7 +25,7 @@ import (
 func TestHashUnitFile(t *testing.T) {
 	f, err := ioutil.TempFile("", "fleet-testing-")
 	if err != nil {
-		t.Fatalf(err.Error())
+		t.Fatal(err)
 	}
 
 	defer os.Remove(f.Name())
@@ -36,16 +36,16 @@ ExecStart=/usr/bin/sleep infinity
 `
 
 	if _, err := f.Write([]byte(contents)); err != nil {
-		t.Fatalf(err.Error())
+		t.Fatal(err)
 	}
 
 	if err := f.Close(); err != nil {
-		t.Fatalf(err.Error())
+		t.Fatal(err)
 	}
 
 	hash, err := hashUnitFile(f.Name())
 	if err != nil {
-		t.Fatalf(err.Error())
+		t.Fatal(err)
 	}
 
 	want := "40ea6646945809f4b420a50475ee68503088f127"
@@ -58,7 +58,7 @@ ExecStart=/usr/bin/sleep infinity
 func TestHashUnitFileDirectory(t *testing.T) {
 	dir, err := ioutil.TempDir("", "fleet-testing-")
 	if err != nil {
-		t.Fatal(err.Error())
+		t.Fatal(err)
 	}
 
 	defer os.RemoveAll(dir)
@@ -88,13 +88,13 @@ func TestHashUnitFileDirectory(t *testing.T) {
 	for _, f := range fixtures {
 		err := ioutil.WriteFile(path.Join(dir, f.name), []byte(f.contents), 0400)
 		if err != nil {
-			t.Fatal(err.Error())
+			t.Fatal(err)
 		}
 	}
 
 	hashes, err := hashUnitFiles(dir)
 	if err != nil {
-		t.Fatal(err.Error())
+		t.Fatal(err)
 	}
 
 	got := make(map[string]string, len(hashes))
diff --git a/vendor/github.com/coreos/etcd/error/error.go b/vendor/github.com/coreos/etcd/error/error.go
new file mode 100644
index 000000000..8cf83cc71
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/error/error.go
@@ -0,0 +1,162 @@
+// Copyright 2015 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package error describes errors in etcd project. When any change happens,
+// Documentation/v2/errorcode.md needs to be updated correspondingly.
+package error
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+)
+
+var errors = map[int]string{
+	// command related errors
+	EcodeKeyNotFound:      "Key not found",
+	EcodeTestFailed:       "Compare failed", //test and set
+	EcodeNotFile:          "Not a file",
+	ecodeNoMorePeer:       "Reached the max number of peers in the cluster",
+	EcodeNotDir:           "Not a directory",
+	EcodeNodeExist:        "Key already exists", // create
+	ecodeKeyIsPreserved:   "The prefix of given key is a keyword in etcd",
+	EcodeRootROnly:        "Root is read only",
+	EcodeDirNotEmpty:      "Directory not empty",
+	ecodeExistingPeerAddr: "Peer address has existed",
+	EcodeUnauthorized:     "The request requires user authentication",
+
+	// Post form related errors
+	ecodeValueRequired:        "Value is Required in POST form",
+	EcodePrevValueRequired:    "PrevValue is Required in POST form",
+	EcodeTTLNaN:               "The given TTL in POST form is not a number",
+	EcodeIndexNaN:             "The given index in POST form is not a number",
+	ecodeValueOrTTLRequired:   "Value or TTL is required in POST form",
+	ecodeTimeoutNaN:           "The given timeout in POST form is not a number",
+	ecodeNameRequired:         "Name is required in POST form",
+	ecodeIndexOrValueRequired: "Index or value is required",
+	ecodeIndexValueMutex:      "Index and value cannot both be specified",
+	EcodeInvalidField:         "Invalid field",
+	EcodeInvalidForm:          "Invalid POST form",
+	EcodeRefreshValue:         "Value provided on refresh",
+	EcodeRefreshTTLRequired:   "A TTL must be provided on refresh",
+
+	// raft related errors
+	EcodeRaftInternal: "Raft Internal Error",
+	EcodeLeaderElect:  "During Leader Election",
+
+	// etcd related errors
+	EcodeWatcherCleared:     "watcher is cleared due to etcd recovery",
+	EcodeEventIndexCleared:  "The event in requested index is outdated and cleared",
+	ecodeStandbyInternal:    "Standby Internal Error",
+	ecodeInvalidActiveSize:  "Invalid active size",
+	ecodeInvalidRemoveDelay: "Standby remove delay",
+
+	// client related errors
+	ecodeClientInternal: "Client Internal Error",
+}
+
+var errorStatus = map[int]int{
+	EcodeKeyNotFound:  http.StatusNotFound,
+	EcodeNotFile:      http.StatusForbidden,
+	EcodeDirNotEmpty:  http.StatusForbidden,
+	EcodeUnauthorized: http.StatusUnauthorized,
+	EcodeTestFailed:   http.StatusPreconditionFailed,
+	EcodeNodeExist:    http.StatusPreconditionFailed,
+	EcodeRaftInternal: http.StatusInternalServerError,
+	EcodeLeaderElect:  http.StatusInternalServerError,
+}
+
+const (
+	EcodeKeyNotFound      = 100
+	EcodeTestFailed       = 101
+	EcodeNotFile          = 102
+	ecodeNoMorePeer       = 103
+	EcodeNotDir           = 104
+	EcodeNodeExist        = 105
+	ecodeKeyIsPreserved   = 106
+	EcodeRootROnly        = 107
+	EcodeDirNotEmpty      = 108
+	ecodeExistingPeerAddr = 109
+	EcodeUnauthorized     = 110
+
+	ecodeValueRequired        = 200
+	EcodePrevValueRequired    = 201
+	EcodeTTLNaN               = 202
+	EcodeIndexNaN             = 203
+	ecodeValueOrTTLRequired   = 204
+	ecodeTimeoutNaN           = 205
+	ecodeNameRequired         = 206
+	ecodeIndexOrValueRequired = 207
+	ecodeIndexValueMutex      = 208
+	EcodeInvalidField         = 209
+	EcodeInvalidForm          = 210
+	EcodeRefreshValue         = 211
+	EcodeRefreshTTLRequired   = 212
+
+	EcodeRaftInternal = 300
+	EcodeLeaderElect  = 301
+
+	EcodeWatcherCleared     = 400
+	EcodeEventIndexCleared  = 401
+	ecodeStandbyInternal    = 402
+	ecodeInvalidActiveSize  = 403
+	ecodeInvalidRemoveDelay = 404
+
+	ecodeClientInternal = 500
+)
+
+type Error struct {
+	ErrorCode int    `json:"errorCode"`
+	Message   string `json:"message"`
+	Cause     string `json:"cause,omitempty"`
+	Index     uint64 `json:"index"`
+}
+
+func NewRequestError(errorCode int, cause string) *Error {
+	return NewError(errorCode, cause, 0)
+}
+
+func NewError(errorCode int, cause string, index uint64) *Error {
+	return &Error{
+		ErrorCode: errorCode,
+		Message:   errors[errorCode],
+		Cause:     cause,
+		Index:     index,
+	}
+}
+
+// Error is for the error interface
+func (e Error) Error() string {
+	return e.Message + " (" + e.Cause + ")"
+}
+
+func (e Error) toJsonString() string {
+	b, _ := json.Marshal(e)
+	return string(b)
+}
+
+func (e Error) StatusCode() int {
+	status, ok := errorStatus[e.ErrorCode]
+	if !ok {
+		status = http.StatusBadRequest
+	}
+	return status
+}
+
+func (e Error) WriteTo(w http.ResponseWriter) {
+	w.Header().Add("X-Etcd-Index", fmt.Sprint(e.Index))
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(e.StatusCode())
+	fmt.Fprintln(w, e.toJsonString())
+}